furthermore, when you e-tag a NIP-33 you could publish the NIP-33 you're tagging to your own relay and then prove that the pubkey that published it was maliciously altering content

I think changing a NIP-33 maliciously like this is much more a cryptographically-sound self-own rather than a problem for people tagging it. 

 Agreed. 

 crypotgraphically sound self-owns are the worst kind of self-owns 

nostr:nevent1qqsvyxucvjxlwsm7u6mtf6esqk2ryzr6qtug9g4mmtsmsmhm2c53qespp4mhxue69uhkummn9ekx7mqzyrafsj7hmweg9ur7zmn6apajdg48hxuskujx53rhrux0ttjcqx84yqcyqqqqqqg4apc28 

 😆 

 crypot