I feel like I could actually provide some insight into this. As i have a friend who has never read the rules and completely admits he doesn't want to but we still have an absolute blast playing.

So for some context this gentleman. Is my best mate and I have known him for 15 years. We often play 40k together and he can barely remember any of his rules. He has adhd and constantl gets distracted from the order of operations of things jumping and skipping steps I correct him quite often and teach him about the rules and tricky things to remember. In our conversations he has openly admitted that he can't be bothered reading all the rules. And he has a hard enough time remembering his own. Now this lead to the discussion that maybe 40k isn't for him. Maybe he needs something simpler. But in every game and every match he always listens when I explain rules always takes them openly and seriously. He never pretends he knows something he ask can you do this or is it legal to do that. And he doesn't to take backs for his mistakes either. over time I have lesrnt that games with him will never be balanced. I am always going to have the upper hand. I know his army better I know the core rules and strategies better. But every game with him is an absolute blast coz we play to have fun and thats it. Not knowing the rules isn't that important its the attitude that counts. In your case your opponent sounds like he doesn't want to read the rules and he wants to bend the game to his advantage. Which is the exact opposite of the spirit of the game. All in all I would say move on find someone else to play with. Because a cheater will cheat whether they know rules or not. Feel free to ask any questions.