It would honestly be safer to farm fucking nuclear bombs than these things.
Hahahahahahahahahahahahah amazing quote... new mod idea?
Jokes aside, I do see your points though. Unfortunately I am unsure of the viability of all three of your suggestions.
Interestingly, I have been brave enough to use this in my own Factory, and it generates a nice amount of tungsten even with 1 tower, definitely feeling worth it as an alternative to worrying out setting up new tungsten mines etc. I have hooked up some simple circuit conditions to only activate the agriculture tower if no pupae exist in any of the downstream buildings and belts. And theres fail safes to simple put any pupae that aren't used straight into the lava. I have been a little disappointed to be honest, because this excessive care has simply meant I have had no babys spawn at all.
I think this is kind of what I wanted the mod to be - its the spoil challenge of Gleba, but you must make it completely failure safe, because like you say, these demolishers do make a mess of things.
In my initial testing I found that a few Tesla turrets could keep them at bay when, and so didn't think they were too over-powered.
You may also find it interesting that the original idea was going to be that if you don't harvest the "trees" fast enough they also spawn, but I couldn't work out that mechanically due to a lack of Lua scripting API for the ag tower. haha. So its still kind of "easy" mod compared to that.
Perhaps lowering the HP of the babies would be the best way to lower the risk of 30 baby demolishers?