With all due respect, I think your son has failed to understand what he has been told by the College.
I worked in Further Education for a long time and I specialised in teaching the students who had spectacularly failed GCSEs. We would never put a student on a GCSE resit if they were 2 grades below a pass. This is because there has been a LOT of research in this area which shows that when students resit they typically only achieve one grade higher on their next attempt. There are obviously some exceptions to this (students who arrived the year before GCSE with limited or no English, students who missed a chunk of schooling because of hospitalisation/illness etc) A student who missed a few weeks before the exams does not fall into that category. Colleges are not in the business of setting their students up to fail. It's simply not good for the student.
A level 2 course is GCSE equivalent. He's not resitting English and Maths because the functional skills is deemed an equivalent. He's not resitting other GCSEs because his starting grades are too low. The course as a whole will be equivalent to between 1 and 4 GCSEs, the number will be determined by the grade he gets overall.
I get that he is frustrated by what he sees as the computing component being too easy. I taught computing and that's a common reaction. However, it's not all Minecraft and playing computer games as many students seem to think. At that level, foundational IT skills, the ones that businesses actually want from their employees are taught. He'll find it's more spreadsheets, databases, systems, hardware, networks, simple coding etc. I've seen plenty of students think, because they've played games all their lives and can work out technology quicker than their parents that everything else is just worthless. However, what they are good at is front end user interfaces. What they don't understand is all the work that goes into making these work. A basic knowledge of data stuctures, coding, protocols and networking is really needed to make any money making side project viable beyond a basic level.