Just to clarify my posts:
I did NOT say there is only one way to do things.
I did NOT say there is anything inherently wrong with or inappropriate about approaching a coach or wanting to meet him.
I did NOT say anything bad would necessarily ensue from approaching the coach.
My first post was simply a reminder that the coach is there to do a job and it is best to let him do it undisturbed. The coach is there to gather information that will help decide whether to recruit a player. He will make his decision about whether to pursue, follow, or pass on the player based on how he sees your son play and conduct himself--unless a red flag pops up from some other source somewhere in the course of his visit. There's just no good that can come from chatting up a coach who hasn't even decided yet if he likes your son as a player.
If talking to the parents to make sure they aren't whack jobs is on his to-do list, he will make the approach after he decides he might still be interested in the player. If talking to the parents is not part of his routine on scouting visits or if he doesn't like what he saw on the field, it's best to let him depart in peace.
As far as the different responses by older and younger parents, I think it is mostly attributable to the fact that older parents are more likely to acquiesce to two realities:
1) You're not going to learn anything useful about the coach by greeting him. The typical college coach has hundreds of parent interactions and is savvy enough not to tip his hand in a brief exchange about any deficiencies he might have in the in loco parentis department. However, you very well might tip your hand about who in the family will really make the decision and what is important to that person.
2) The coach doesn't want a relationship with you, and your relationship with him will effectively end when your son's recruitment is complete. The coach knows well that baseball is a game of failure and most recruits will not have the careers they envision. He will keep all parents at arm's length because he knows there's a high likelihood he's talking to a future disappointed parent of a player who got benched, cut, or transferred. Same reason farmers don't name their cattle.
Letting these two realities sink in tends to dampen one's need and desire to interact with the coach. And yes, it takes a while for them to sink in.
Are coaches "okay" with being approached by parents? They know it comes with the territory. They know today's baseball parents are more involved, for better or for worse, in their kids' lives. They tolerate it. Doesn't mean they like it. Doesn't mean your interaction with him has any chance of helping your son.
And my second post--about the kid who throws 95--was an acknowledgement that individual situations vary. The more attractive a recruit your son is, the more parental interaction they'll tolerate. But it doesn't change those two realities I just mentioned.
Best wishes,