He only said he'd consider it.Except Brown essentially said he'd nominate Jackson OTL. And the Convention wanted to put a candidate through already.
and, as kevvy pointed out in the actual update the party split on other candidates instead of all rallying behind someone. I don't even see it as "unlikely" let alone ASB
And barely anyone in the party would support Jackson. Bob Casey is the most likely. It doesn't matter that they wanted to put a candidate through, if they would have confirmed Jackson, they would have confirmed almost anyone.