Hey, M.. I am a speech pathologist, and I actually specialize in treating kids with swallowing and feeding problems. My heart goes out to you! I know it can feel so defeating when your child has trouble with something as fundimental as eating! You are doing your best, I'm sure. I want to give you a little info, and I urge you to talk to your doctor or therapist to clarify some things for you. Firstly, aspiration means food or liquid is going down the airway, to the lungs, RATHER than into the esophagus where it is supposed to go. If your baby is really aspirating, that is a dangerous problem. Food shouldn't be in the lungs--it can cause chronic pneumonia, choking, or worse. So if your son is really aspirating, you MUST MUST MUST find out how to prevent that. That may mean giving him only very specific types/consistencies of food, or even considering non-oral nutrition (i.e., a small tube in the tummy) TEMPORARILY until he gets stronger and can swallow safely. Aspiration is not something to fool around with. I am curious as to how they diagnosed that. The only definitive way to do so is with a special XRAY test called a Modified Barium Swallow. You can get some idea of what is going on by a clinical exam, but if the therapist thought he was aspirating, she should have set up an MBS. Maybe they only think it happens once in awhile...but still. They MUST give you more info on that.
Yes, sometimes chronic reflux can cause damage to the swallowing mechanism, but sometimes it just causes kids to have what we call a feeding "aversion," meaning they just avoid eating b/c it causes unpleasant feelings (vomiting, etc). Eating and talking are not necessarily tied together, but if a child has a speech/language delay, he may be delayed in other areas. One thing we see is that kids with developmental delays may have "sensory" issues. This is often manifested in eating. For example, some kids don't like certain tastes and textures in their mouths--I know, we're all like that, right?! But some kids have it to an extreme (e.g., won't eat anything crunchy or slimy, will only eat bland food, etc).
Since I don't know the whole story, and I haven't seen your precious boy, I don't want to undermine what the therapists have told you. But it does sound like you need to clear up some things. If you're more comfortable with your doctor, you might call him/her for advice. Maybe the doctor can look at the therapist's reports and give his opinion.
Good luck, M.. PLEASE email me anytime about this. This is something dear to my heart, and I want your son to get the best care he can. I am happy to try to find you another specialist if you continue to be unhappy with the clinic.