I’ve been lucky enough to avoid physical limitations so far, but I’ve done a lot of long-term travelling. Are you craving a bike tour specifically, or is part of it wanting to be nomadic/outside/survival mode for awhile? You can always go rubber tramping/dirtbagging with a vehicle, stay at campgrounds and bring a bike with you to go for shorter rides. Hell if you can walk decent and wanna get real rugged, there’s always hitchhiking. I’ve met plenty of haggard old men with injuries and lives full of manual labor and drug abuse who are still getting around. There’s a million ways to travel.
Aw man, sorry you’re going through that. It sounds like you both just really need some space to calm down and process. I also get very snappy/aggro and tend to start fights when I’m anxious. I’ve pushed my partner away during health scares as well (I’m in therapy and always apologize after tho) When I do, it’s never actually about my partner. It’s me feeling anxious, wanting space, feeling guilty about receiving help and wanting to pull away and isolate to deal with my emotions. Don’t take it personally and it’s perfectly normal to snap back at someone when they’re being a bit of an ass. You didn’t do anything wrong. Hopefully your partner just needs some space to calm down.
Also, when you’re both in a good headspace, it may be helpful to ask about why they want their mom to help them instead. He might be subconsciously guilty and not wanting to burden you.