It's okay to use /spit simply because u think the player is supporting greedy activision.
Who says you're not allowed to do it? Its simply an emote blizzard have made available in-game, so therefore it wouldn't be wrong to use it.
This is the best way to make retailers that bought the mount not wanna use it and support blizzard cash shop,
so i think someone should make an addon that automatically /spit whenever a store mount is running by.
Another thing don't invite players to dungeon groups that are boosted chars.
Spread the word!