Bum,
There is something of a contradiction in saying, "average scout that cares [about velo] = 0" followed by, "Don't get me wrong, without it [velo] you're not invited".
It would be more accurate to say, "Every scout fundamentally cares about velocity". Yes, tenacity talent, heart....many factors that can't be measured by radar...are deeply important. Probably that is why so many mistakes are made---heart, character, and willpower don't show up on radar at all.
Although it may no longer be of interest to you (and, actually, my interests are starting to move on now, too--my son just signed his letter of intent this morning)....but, anyway, if you think carefully about how to use PG data it can be helpful to lots of HS'ers who are coming up behind your son and my son.
Thus, it's not about "ave HS RHP velocity". For HS guys who currently wonder where they might fit in at the next level it's about: "what is the ave. HS velocity of RHPs who were eventually recruited by school X, Y, or Z?"
I very much doubt that the ave D1 RHP velocity, that is, averaged over all 300 D-1 programs, is 88 mph. In fact, no matter what the actual average is, that is not the important number...from top to bottom of the entire spectrum of D-1 programs the RHP velocity varies a great deal. At the highest end of the D-1 spectrum average RHP velo is higher than 88 mph and grades probably don't matter quite so much. At the lowest end of the D-1 spectrum, average RHP velo is down around mid-80s and grades matter more than athletic talent.
Again, you can dismiss all of this if you like, but for those HS guys who are still trying to figure out where they have the best chance of fitting in at college level, it's too vague to say, "without velo you're not invited". There's a "right place" for most if they really want it. There's no line in the sand, it's all about finding the best match between program level and individual athlete.
In fact, you said it yourself...velocity is one of your three most important predictors of where a player will wind up, so individual players should use that number as part of their road-map to know as clearly as possible what sort of future is realistically open to them.