I managed to make a stable dense ore age by purposefully adding in instability and a bit of luck. If you add into your age charged and scorched earth you can greatly reduce the chance of getting meteors, spontaneous explosions and decay. Just make sure you have all the required symbols + those two instabilities.
It's like what Auchioane here said in the quote. You have to balance out the Dense Ores symbol with other symbols that compensate the instability added by it. Currently, you can add a bunch of Charged/Scorched Earth symbol and 3 of them are, most of the time, enough to compensate 1 Dense Ores symbol... Most of the time, anyway. Meteors are annoying, but relatively easy to protect against.
Your best bet for mining in a Dense Ores age is building a frame bore, setting it, chunk loading it, and forgetting about it. Just let it run, for however long that world lasts with the instability. You can protect it against meteors with Reinforced Stone, Warded Stone Blocks, or MFFS, and the odds of it beings stricken directly are quite low. If for some reason it gets destroyed, well, such is the price of greed. Alternatively, you can just keep creating new Dense Ores ages, stacking as much Dense Ores symbols as possible, and quickly setting up a ton of quarries running off of a lot of power so they finish quick, retrieve them when they're done, and create a new age. Rinse and repeat. Turtles are great, too, because you can't be too mad about losing them.