What makes you think he "hates it"?
Every time something like this happens with Marshawn someone makes a baseless claim of how he's immature and he should leave since he hates the work so much.
Hating an aspect of the NFL most players don't like =!= Hating playing in the NFL.
Marshawn doesn't like the media, and so he exploits loopholes in his contract so he doesn't have to deal with them directly. What's wrong with this? Do you want the NFL to mandate NFL Players to give full and real answers to their already mandatory media conferences? Cause frankly that is something I vehemently do not support.
He clearly likes playing football, he wouldn't get so excited after making baller plays if he didn't. He wouldn't continue to play one of the most expendable and dangerous positions if he didn't like football.
To contextualize this for people that have never played sports, it would be like if you were working a dream job, great pay, you're happy as can be. Only problem is that once a week you have to talk with an independent associate about what you're doing/are you working to your best ability/and all this bullshit. It's annoying, but it's in your contract and you do it to keep your job. Now, you can answer the questions truthfully, or you can just give a monosyllabic grunt with no repercussions. You might be inclined to at least try to answer the questions in at least a half-assed manner. But consider that this independent associate has a wide audience that he/she publishes what you said to. And the associate is a dick, and takes things that you say out of context, or tries to make stories out of things you said from nothing. You might be a bit more inclined to just murmur or bloviate.
Like, I don't get it. Marshawn gets criticized for being "immature", which sure, that might be true. But I just don't get criticizing him over not taking the media/these fines seriously. Would you rather just have him go on about "oh gee thanks God for this opportunity thanks mah aww shucks I just love my team we played well together yada yada". Cause imo I'd rather have the grunt. It's just as bullshit in a tenth of the time.