If that warning is gone by Monday, it could've been just an error (or some may say, an "error"); however, with the recent notice that he's available now and people eager for things after Comic-Con, I wouldn't be shocked if he's that close to selling out.
This is the most impressive Deadpool statue out there -- regular or EX -- and while some have said 2500 is a high edition size, it's really not for how popular the character has been in recent years for Marvel (let alone a ways back!) The EX "sold out" a long, long time ago, and while a few are converting now -- which is expected -- odds are people who were on the fence are picking one up now.
There have also been a lack of immediate pre-orders after Comic-Con, which means that most people have at least a year or so to get any upcoming pre-orders they may be interested in from SDCC and may want to grab something in the meantime.