I am contemplating converting my Core node to Knots, because I do not want the idea to be pushed that nodes can be used to store CSAM or malware payloads.
It would be disastrous for the entire community if somebody executes this use case. We will be pushed into an enclave like the Monero community.
You're far too late to worry about it. More than 1 decade ago someone already push Wikileaks cablegate data on Bitcoin blockchain[1].
I hate to repeat this again and again, but Knots does exactly nothing against spam. Please educate yourself, e.g. reading the Bitcoin mailing list discussion.
Knots does not stop the spam from entering the blockchain, but it prevents it from being stored on your node which can remove you from liability in cases like what I mentioned.
It would be great if your (or anyone else) could show reference that Knots does not store arbitrary data. Last time i checked, Knots only refuse to relay TX that contain arbitrary data.
[1]
https://www.reddit.com/r/Bitcoin/comments/1bw9xg/data_in_the_blockchain_wikileaks/