Splitting the baby is not a fun job. I do not envy you, slowpoke. I'll try and communicate how I see this decision and its basis and what it means in regards to what you are asking, though.
Having a hotter head on this could've had some serious long-term ramifications in general. This decision respects the natural boundaries you have as a result of the fundamental compact that makes FTB possible: FTB's agreement with mod developers that it will only distribute mods it has the permission to distribute. That agreement puts a clear-cut boundary on FTB's reach such that FTB can't arbitrarily dictate to mod developers what exactly will be in their mods, lest the developers pull their support. This is the rational and pragmatic view, and while it can be wedded to a moral view as well (e.g. FTB ought not dictate what mod developers do with their code) it isn't necessary to recognize where the hard line not to cross is in this instance. FTB decides to be "world mod police" and pushes too hard, support can be pulled and wreck the foundation of the packs. It is thus not in FTB's rational self-interest to overstep.
FTB's other primary "duty" (I use the term lightly, this is a hobby after all) is to provide well-curated packs of mods that play nice together. There are other, lesser considerations like "do the aesthetics of the mods align" and such that go under the penumbra of "well-curated", but let's not mess with those at the moment. If fundamentally the mods absolutely refuse to run together for whatever reason, FTB has to make a decision on inclusion in the packs. This is plain logic and should not be an item of dispute for anybody. Initially this can be discussed as "the code does not permit these mods to run in tandem", but this current set of circumstances has extended that even to "the mod developers for the respective mods have determined they do not wish to invest the effort in making them compatible". As I already said, FTB doesn't have "world mod police" duty to force the mods or even the mod developers to play nice together, its only duty is to ensure the packs it produces are internally compatible and that they don't produce adverse effects on player systems. When this is not possible, that is where FTB needs to step in and make a judgment call.
That sets the boundaries for the proper area for FTB to make this call: when circumstances render it difficult-to-impossible for FTB to produce packs, or when the mods themselves are at risk of adversely impacting player systems, FTB is obliged to step in and deal with it. Outside of that, pragmatically speaking, FTB doesn't have much of a foot to stand on in prodding the mod developers. Again, morally speaking FTB is certainly "allowed" to take all manner of stances it wishes, but that has to be weighed against the tolerance of the mod developers whose mods are included to be dictated to before they pull their mods from the pack. Thus it behooves FTB to not overreach and worry about what happens in situations where the mods are used outside the environments FTB provides.
That's the balance being stricken here with this stance, I think. FTB can't tell the mod developers what they will do with their code. They can only push to the extent that such things impact FTB's ability to provide its service. DRM and anti-inclusion code are totally aside there, because they do not impact FTB or FTB's user base. It could offend somebody's moral stance on it, but the mod pack operations come first because the mod pack operations are easily and readily justified without moral wrangling. The only pragmatic injection here comes from FTB's reputation and people's projections on it and how that may affect their opinion of the packs and willingness to play them, but you can't please all the people all of the time.
Where the fuzziness comes in, and where it's hard to dictate a standard policy, is where you start having to look at patterns of behavior and the like. If a mod developer is consistently being curmudgeonly in an adverse manner to producing the packs, but whenever called out on it eventually complies, is there a point where you just say "no more of this crap" and pulls their mod entirely? What about when the mod developer is merely dramatic/histrionic on a regular basis? What about the mod merely being controversial? (If you want an example of how "dramatic" and "controversial" vary, GregTech's a good measuring stick for both: GT's initial inclusion in the pack is merely "controversial" even if the forum posters themselves get "dramatic" about it; Greg's spats with KL, Soaryn, and now mDiyo are "dramatic".)
I think the fair thing to do in this case is what is being done. Communicate the expectation first, then enforce it. Previous hullabaloo aside, everybody's slate gets wiped in this regard. Further incidents will be dealt with as communicated. Mods that the developers communicate should not run together will not be included together. Making the FTB Team's life consistently difficult may be grounds for total removal from the packs. Go forward from there.