It is hard to say for aerospace engineering what the cutoff would be as admission is based on number of applicants. Last year my son knew some high school students that had a 3.8 and could not get into mechanical engineering at Pomona. It may not be a bad idea if he really wants to go there to start off with a clean slate and go to community college first.
The important question to ask if he could make it through the program if his GPA is a low B. Not that grades are everything, but they are pretty good indicator of success in a tough engineering program. Engineering at Pomona is brutal and if he is not strong in advanced math he won’t make it.
My son came out of high school with a GPA of 4.25 and 40 community college units. He was super strong in math. He spent a year after high school in community college and transferred into Pomona with a community college GPA of 3.83. The engineering program at CPP is making him work really hard to get good grades. My son always thought he could do better than Pomona until he got there. He found that the students in the engineering program are all brilliant and that it was more intense than he thought it was going to be.
Some schools admit incoming freshmen as pre-engineering which is a good move. That way if you don’t make it you can transition into another major with minimal unit waste. Cal Poly Pomona doesn’t do that and they have you take basic engineering coursework early. Unfortunately, if you flunk out of the advanced math like so many do then you have all those classes that do not carry over to another major.