Left field...You're asking if we think the statement in quotes is a spoiler?
Honestly couldn't tell you. Maybe it's a spoiler to those familiar with the premise of the story? Omega is an enemy in a lot of FF titles, so doesn't seem too spoiler-ish to me.
Unless you live under a rock and have no idea who the playable character in Dirge of Cerberus is I don't see how that sentence spoils anything. Like Delta said, the only spoiler could be that Omega is in the game... Just like it's in almost every Final Fantasy game... And that you can fight him... Just like in almost every Final Fantasy game. And if you know so little about the Final Fantasy series that you don't know Vincent is the playable character or that Omega is a reappearing enemy then you probably don't care enough about the series for a spoiler to bother you.
ETA: Of course, we're merely given a statement without context. It sounds like that statement was a reply to someone's statement. In that case it could be a spoiler. For example, if I asked," Is it possible to bring someone back from the dead?" And you replied with that statement it could spoil the story because you're telling me Vinnie is killed by Omega then returned from the dead later on. Which is a spoiler. But the statement alone without context isn't a spoiler.