I would run the net price calculator for Syracuse to see what the EFC is. Syracuse has a very strong geology department, and is literally across the street from SUNY Environmental Science and Forestry. My concern with transferring to LACs is that the course availability is extremely limited, meaning there will likely be difficulty with scheduling. Many LACs also do not teach some of the courses which are all but required for employment in the environmental science world, or teach them at an extremely cursory level (GIS is easy to learn, but knowing which statistics to input into GIS and whether the output makes sense is far less intuitive.)
With a 4.0 from a decently respectable university, he is competitive for schools with solid to excellent financial aid which accept a number of transfer students. I know Vanderbilt accepts lateral transfers (that is from US News top 30 schools). I don’t know how they would treat a 4.0 from Maine, but it is worth a shot as is the University of Miami.
Given the relatively low number of courses needed for most geology grad programs, the University of Maine does seem to offer the proper courses based on what I’ve seen on the website. If your son could get a summer research position or work with the Student Conservation Association (apply before Feb 2) he would drastically increase his competitiveness at good environmental geology grad schools.
What courses has your son taken in both fields? Also include complementary courses such as Calculus, physics, chem, etc.