There is research on the benefits of gaming, and the parents should read it. If the child doesn't know about it, he can do some research and supply it to the parents.
If the son can calmly and politely explain his reasoning for wanting to play games, and demonstrate that he's done the research into why gaming can be good, then he may change his parents' minds.
If the parents allow their child to openly play video games, for a limited time, then they'd likely be eliminating their son's need for subversive behavior. Since he'd be allowed access to his laptop at times other than when doing homework, he'd be able to play without cutting into his homework time.
One of the import things the son will have to do as part of this discussion is show that he can get his homework done without it being an issue. If he's currently having trouble getting his homework done, his parents aren't likely going to "reward" him with video games. He needs to demonstrate a level of maturity that shows he's willing to work for the things he wants.
A great way to get homework done is to specifically schedule time in your day to work on your homework. Work somewhere that's as free of distractions as you can, and plan on doing homework.
While working on homework, break it up into manageable sections. You don't have to do everything in one straight block. Pick a goal that will take 15-20 minutes. Once you've finished that goal, take break: read some Facebook or Twitter, get up and walk, get a drink, watch a short YouTube video, whatever you're allowed to do. Then, after a couple minutes, get back to the homework and set another short goal.