Im sorry I've had to be really blunt and direct (you've taken what I've said well - many wouldn't).
But genuinely, few people who get into the industry via the graduate route. You have to stand out that way.
It's getting a shit job at a much smaller company to start. Often having first done something else to demonstrate willingness to work hard, take responsibility and work independently by showing initiative that's the stepping stone in.
Graduate places are hard to get. Competition is tough.
They are people who have had placements, can show leadership in other extra curricular activities completely unrelated to computing, can show almost a 'portfolio' of what they've done - especially if it's off their own back, people who can show they are still learning different skills and languages etc etc.
If your son has just about managed to stay the course on his degree and doesn't have other stuff going on, he's not going to get those places.
He should look at stuff like maybe tech support. It's not always a great job but there's always people who need that and if you can get your foot in the door that way at a company other doors may start to open up.
I know DH didn't get his first proper job in programming at a tech company for about 6 years out of university. He worked at other companies as a shop worker, tech support type role, then building websites and then started to get into programming roles. He was doing his own things on the side throughout. What he did do was kept applying and changing jobs and getting new skills - this is not necessarily frowned on in the industry as long as you can demonstrate it's part of your learning curve.
It's not a race. Some people get a fast track. Others don't. In the long run some graduates end up getting comfy and stay in the same role for a long time and eventually become worse candidates than those who take the longer route who gain a wider range of skills and work experience along the way.
As long as he understands this, it might be easier.