No, he's not. Not in the way he's saying it. Every single poll is showing him losing at this point. Many political leaders, including those in his own party, have dismissed his claims as nonsense. As he always does whenever he's embarrassed in public, he's simply laying blame for his failure on something — anything! — outside his own incompetence. Unfortunately, his core supporters lap it right up.

Saying the election is rigged with zero evidence is "saying it for the wrong reasons"

No, he absolutely is not. He is acting as a giant crybaby, and he will continue doing so after the election, with disastrous consequences.

He's absolutely not right.

It's fine to question things, but just saying "it's in doubt" with no argument is just Trump style FUD.