Again, you're talking about something that hasn't happened, and that you know nothing about.
And what if he is a jounin? What does that mean? Just because he's a jounin that doesn't mean he could defeat someone like Sasuke. I could name many jounin who would be killed in a matter of minutes by him.
I agree that the way he defeated Deidara was extremly cheap and ridiculous. But hey, that's how it is... Did you expect the main antagonist to die so soon? Kishi can't do that.
Right now, Neji has absolutly no chance in winning against Sasuke. If someone like me, who dislikes Sasuke adimts it, it's because I have good reasons to say it. When I know something is true I don't get my personal opinion get in the way.