I looked into it months ago, and I think the argument from "bip110" was: "yes it was, and it is still possible to inscribe csam. BUT:
- default settings matter
- allowing 100k by default makes it possible to incsribe it as a continuous file (instead of having to break it down in multiple ones). This makes it easier (less technical) for people to process the data to "visualize" the file as jpeg
- setting that as default makes it easier and therefore send the signal that you welcome more non-monetary uses of btc

I spent lots of time looking at the whole debate dude, and as a stupid pleb this is where I ended up:
I like the intention/spirit of bip110 but I don't think it's the best way to achieve it (let the fee market decides). Still I switched to knots because this episode showed that something in the internal politics of core is not right