As you have heard, don't burn bridges. Not all coaches are like this. My son dealt with multiple coaches in three P5 conferences and all followed through just as they said. As much as we did not like it, they were all either we have an offer or you don't fit into our plans for what you are wanting. By that, two wanted to redshirt him as a freshman and that was not son's plans. I respected the conversation though. But you must understand that we had the upper hand. Right now, they have the upper hand on you and your son. They hold the cards. I would think you are not going to get a scholarship at this point but a preferred walk-on and some academic money which is why they need to check on some things. It is probably best for your son to do as you have said and have conversations with juco coaches. If the perfect offer comes from a D1 then you can back out if you decide to. 90 is good for rightie but not great for top level D1/P5. Understand some of their question may be if his top is 90 now and has made big strides as you say where will he ride this spring 85/86. If you son is bound on one of those schools, then have him call them. If not, take the juco route. Best of luck.