Well...he had the luxury of not being in a battleground state (California). He also genuinely did not believe the 180 degree turns on a host of issues were sincere and did not believe he would deliver on them and was a scam artist - given his history and past remarks, that was a perfectly rationale assumption. But Trump did deliver, before our very eyes...and Shapiro admits it and isn't at all mad about policies he has wanted to see implemented get implemented simply because it is Trump doing it, unlike others...he's glad they are in place.
There were a lot of places Trump carried where he won by larger margins statewide than Republicans have before, but lost individual areas or won them by much smaller margins where Republicans typically have a blow-out - Ben Shapiro has influence over these people where his podcast is popular - the college educated, intellectual conservative wing of the party that Trump "rubs the wrong way." If this announcement brings a number of these folks back into the fold, that could be most helpful for holding marginal states.
Refresh my memory: Did Shapiro’s writings in 2016 only appear in California? Did he write that his opinions only applied to California voters?
His judgment is what is forever tainted, not his current opinion. That he has come around is good, as I said. That he continues to think his opinions should be provided to us, instead of the other way around, is where he is wrong.