Absolutely nothing is stopping alternative currency developers from integrating their stuff into Nostr. Its an open protocol. There is simply no demand.
That said, using monero in this context would be pretty foolish from a privacy standpoint
Discussion
You can implement Monero tips in a manner that is private. For example, +1 anonymous increments per donation regardless of size. Your client could take care of broadcasting +1 increments.
You could also have ranges/levels of a note "heating up" the more tips it gets to be even more vague. You could even have optional transparency and let users decide where they want to reveal they tipped.
If you want to be really safe, only allow tipping to a sub address tied to a particular note, with nothing broadcasted publically. It would work like normal anonymous Monero donations.
If you have better ideas, or can see problems with any of this, please leave a comment here:
https://bounties.monero.social/posts/94/8-498m-nostr-client-for-monero
Seems like an easy ~$1200 pay day
