Does your son or do you pay for the program? the coach has just as much responsibility to talk to you as anyone else. This isn't a college or even high school, you are paying for your son's development and need to make sure you are getting a return on your investment. You can certainly send your kid into get answers, but in the end you are responsible for your kid and you are financing this, plus he's a minor. Partly the reason coaches talk about not wanting to talk to parents and that you should have your kid handle this, is so they don't have to be held responsible for what they say they and the program are about. it's similar to an employer putting out that you shouldn't discuss your salary with other employees, if they can get you to prevent yourself from finding out, it only helps them.
Also, you want a complete answer and honest eval, most kids are not sophisticated enough to know when an adult is blowing sunshine up their you know what's. Nor do they often want to ask the tough questions since they might hear something they don't want to. You need to think about what your kid is capable of, how many times have you asked them about a teacher meeting, asking, well did you ask about this? "no". Did you talk about that. "no". Only really the most sophisticated teenagers who have zero self confidence issues will get complete information.
Good programs set up meetings throughout the year with the player to discuss these things, I think if there hasn't been any, you certainly can ask about it. These meetings happen more often as you start getting to 15, 16 and 17u, and should increase with each level, not just because of college, but also unlike 10u-13u, you aren't' usually guaranteed a roster spot the next year, so you need to know where you stand. Start with just asking if the coaches are going to give each individual player an evaluation, and ask when. If you get a brush off answer or something like "at the end of the year", you certainly can ask if you can speak with them sooner as you have to have time to set up any plans for helping your kid, etc. What good does it do you at the end of the year and then, gee tryouts for a year away are next week in July and Aug.
That being said, as long as you are respectful and don't act like a "baseball parent". And don't start giving advice on how they should run their own business. Then any coach should have no problem discussing your son's future in baseball, they should be about helping him reach his goals. If you are worried this could negatively affect your son's role on the team etc. you are in the wrong program.
As a final thought, your son's journey to college baseball and recruiting if not at a top level, is going to be driven 90% by you and your kid, not a travel ball coach. So get what you can out of them and don't leave it to chance that it will happen. Think of it as looking for a job, coaches often are more references than recruiter, are you going to leave it up to private recruiting firms only.