What happened in Virginia must have emboldened him.
This is true, though I think the race would lean toward him even if McAuliffe won in VA. Now he has pretty much nothing to fear if he does make a bid. As for myself I'm on the fence about who to support if he runs. I usually oppose Republicans and Phil Scott and Charlie Baker are more my type, but Sununu doesn't seem too bad, though I wish he'd made NH enter the interstate climate agreement that Baker, Scott and Larry Hogan put their states in.
I'm a moderate Republican who voted for Biden too. But if you're at the point where your heart wants the Democrat to win most of the time, that should tell you that you're not a centrist Republican, you're a centrist Democrat. Sununu is very moderate. Any self-described moderate Republican should support him.