Well, quote button without this mod is shown. But, as every new post posted with AJAX threads is last at the moment of posting (I really don't have that active forum to have more than one new post every few seconds), showing of quote button is omitted.
With this mod off, this works just fine, so if it could be checked if AJAX thread mod is used for posting, you could stop plugin from omitting quote button. Similar to welcome thread, where plugin checks if there's something in username, or not.
Problem is, how to check if AJAX thread is used to post certain post.
Thing is, on very active threads too many posts would be without quote button to allow further use of this mod.

And I really like this mod.
EDIT: Thinking about it, if you could go other way round, to leave quote button in postbit, but when user tries to use it on last post in thread, to block it and give message that last post in a thread couldn't be quoted. This would work with AJAX thread without problems.