Probably. What's at root here may be the idea that Jeb was more qualified than his brother and had a steadier temperament and more dedication -- that he was the one who should have run. The rumor was that Poppa Bush thought so.
It's a debatable point. It may just mean that Jeb would have been more acceptable to the establishment.
And the discussion is a bit like people arguing over which Kennedy brother would have made the best president when one doesn't think any of them as that great.
At this point though, Jeb seems quite tired. Whatever focus and energy he may have had dissipated over time.
I don’t doubt that Jeb would have been better President than GWB (LOW bar) - but regardless, he’s an awful prospect now.