A rush or a great opportunity?

I think that a clear picture of what type of school this is, is very important in order to keep things in perspective. This could easily be a relatively small private school where the middle school and high school are ajoined. Many of these smaller schools can barely fill a roster with players that can throw and catch, much less hit!
That being said, I can't imagine a 12 year old playing with our JV team. Any program that is above a 1A or 2A should be no place for a 12 year old.

Working out or practicing with the JV team will be great for an advanced 12 years old kid. although, I don't think that playing games will be good for him.

I guess I don't see the big deal. My son was fortunate enough to hang out with a D-I college team when he was 10 years old...
...and coach actually put him at 2B during infield/outfield practice one day. The SS was...
...now MLB player Ty Wigginton.

The work habits and respect for the game helped him...
...and I suspect even hanging out with kids 2-3 years older will help your son (just be ready for some new words he may learn).

So far, you’ve all had thoughts and perspective that I can understand, if not agree with. But what I just can’t wrap my brain around is, I’ve never seen nor heard of a HS coach who ever had enough time to work with his players. So, what motivation would he have to take what little time he has to develop the players already on the team, and give it to a kid, who except for a very few extraordinary circumstances, wouldn’t be able to help the team for at least 2 years.

Except for the extraordinary circumstances such as Floridafan mentioned, I’m guessing its much more of a thing where someone’s kid is getting a favor because the coach somehow “owes” dad. I don’t mean that in necessarily a bad way, but I can’t imagine every 12YO in town would be able to get that same thing.

My son’s JUCO coach always had his son practicing with the team, and every once in a while a couple of his pals would be there too. And I’ve seen other coaches of teams where they let their kids who definitely belonged in leagues much lower, allow their kids to work out with the team. That’s OK because its up to the HC what goes on. But to be draggin’ kids off the street with no ties whatsoever to the team just seems wrong to me.

Insurance/liability issues? What if the kid got hurt or hurt someone else?

How about medical clearance? All the HS kids have it, but the 12 year old is not cleared with the District.

Really doubt that practicing with a JV team will "rocket" anyone past anyone. All it really does is take someone's reps and tick the other players off...

Much better off picking a top travel team or local baseball coach/clinic or exercise guru to make the kid stronger or work on his tools.

Is this kid as big as the 14 year olds? Can he throw as hard? Run as fast? Are his catching skills as good? If he really can hit JV pitching, keep up on the bases, and catch as well, then this JV team must really be bad. How can practicing with a bad JV team improve anything, except having him learn some words and behavior that Dad won't necessarily approve of?