Colloquially, we call this staking. I think it's a cool idea and we'll probably add it at some point but the UX around that is probably tricky and hard to communicate.

Maybe you should consider who is marking the comment as spam, someone in a flame war with someone might make sockpuppet accounts to mark a specific users posts as spam. Maybe only take spam markings from users who have reached a certain threshold of recieved sats, in combination with a minimum number of months account has existed. Whatya think?

well most nodes have a min fee of 1sat so transmission of 1 sat for comments may not scale very well and if cheap enough for comments it may not be cheap enough for spam prevention

But why tho? This is really complicated and 1 sat is very little.