An atheist could say based on all his scientific knowledge, he is certain there is no God. But he can't prove this, so the non-existence of God is still his opinion on the matter. If somehow he can disprove the existence of God with complete certainty, then yes, now it would cease to be an opinion and become fact.
Well, that's why the weak (=clever) atheist will say "there is no reason to believe he exists" ;)
Not including an object into your worldview, for which there is absolutely no evidence (like the flying teapot, or whatever), may technically be called an opinion, but it's probably the most reasonable and "close-to-knowledge" opinion there can be.
It can be argued all day long why such a stance would make complete sense, and rebuked rather quickly why the opposite doesn't.
If you claim there's most probably a flying teapot on top of some meteor in the next galaxy, I'll say you're wrong, not because I know 100% there isn't, but because you'd have reached that conclusion by some kind of convoluted logic that doesn't make sense.
Now that all applies to theistic claims, as well, as far as I know, but I haven't yet studied that stuff so let's leave it there ;)
Basically, what I think what you are getting at is that one can hold opinions about facts, and/or that one can hold opinions that also happen to be facts.
Eh... that's a rather... "political" way of putting, but yea, yea, like with your three examples above.
Maybe using the words "judgment" and "taste" would be less confusing - they'd both fit into the Oxford definition of opinion, too ;)
So how about you don't claim that about Jordan, but about some noob kid in the neighborhouse... it'll still be an opinion, but what chance would it stand at being any true?
I'm pretty sure you could make a very solid CASE for Jordan, though.
So I think we've established that opinions (of the first kind) can be attackable, debunkable, and right/wrong.
In that sense, if I take something that passes for an opinion, not fact, and say "that's false"... am I automatically wrong for being that way?
Or would you first have to show that that "opinion" was, either a subjective opinion, or actually pretty damn well supported in contrary to what I'm saying? Or if not pretty damn well, at least makes enough sense not to be indisputably "false"?
If none of that is the case, I honestly don't see why I can't do that, and then let the other one defend their opinion if they can.