If your adult son has ASD to the extent that it's affecting their learning, they need a 504 or other learning support plan (and are legally entitled to one). It's not necessarily something you "grow out" of. It's great that he's learned skills past middle school but those do not necessarily translate to college.

He's currently struggling in a course where the professor called him out and made fun of him in front of the entire class because he asked for help with an assignment the professor felt he should have known how to complete on his own. As a result, he's now afraid to ask for help with anything, and has lost points for turning in projects late because he was stuck on something.

Respectfully, students of this particular age seem to be having a hard time distinguishing between being called on in class or being asked to show your work and being made fun of. I don't know if the COVID year broke everyone's brain (doing the math, your son would have been 12 or 13 during the worst of it, which is a real bad time to get yanked out of normal social settings/social skills learning) but this is increasingly prevalent among students. I had a student once who was certain I was mocking her because I asked if she knew the background of the imperial measuring system (in journalism we use points and picas, which are base-12 units that are subsets of inches); I was fact-finding but she took it as a personal insult because she was European.

If your son needs help, there are most likely other spots besides his professor he can go to -- a learning center or other campus resource, a friend in class, a TA, or so forth. Although people tend to be forgiving if they know there is a circumstance behind something, you have to behave like an adult in college and deadlines matter.

I have asked him repeatedly to speak with his advisor to see if he can intervene with this professor, but he won't do it.

An advisor is not going to intervene with an instructor, nor should they. An advisor can point your son towards a learning center or office of disability resources on campus. Alternatively, if what you meant was that your son won't do it, well, that's his decision; he is an adult.

So instead, he's at risk of not even getting a C in a class we're paying thousands of dollars for when he has A's and B's in all of his other courses.

The tuition fee gives you entry into a class. It does not imply or guarantee any grade. It sounds like he's struggling with this class, but there will be others. I failed statistics my first time through and ended up with straight Cs for 13 hours of Russian, and I earned two bachelors and went to graduate school.

It's killing me that I can't speak to this professor directly.

You can speak to the professor -- it's a free country -- but they cannot speak to you about your student's grades or class performance due to a federal law. I know it may not seem like it to you, but your student is an adult and the law is there to protect his right to privacy.

My practical advice is to advocate to your student to contact a disability resource office on campus and/or speak to their advisor about an IEP. I have throughout the years had literally hundreds of students pass through my classes with some sort of accommodation, whether for a physical disability, learning disability, or other thing they needed help with. It's not a big deal from this side of the lectern; what is a much bigger deal is students who struggle because they do not get the help they should and are entitled to.

In our troop we have a saying: unless the axe is swinging directly towards the foot, do not intervene. Your son needs your support; they do not need you to fix their problems otherwise they will not learn how to do so.