I just went into a whole big thing about that ammo topic in response to a question in my "Changelog" topic... won't repost it here but you're both basically correct and... I personally don't think it matters a great deal. Feel free to read it if you like. It's an edge case that needs a solution, and I think the current one works fine. I haven't heard of a better one that doesn't then introduce another edge case problem.
Page 58 - Clarification
Crawling only allows 1 Move
Changing elevation requires 2 Move.
Is it therefore impossible to change elevation while crawling? Maybe a simple note stating that a Crawling character can change 1 elevation if they spend their whole movement doing just that?
Just like running, you can attempt to gain (a single hex of) additional movement while crawling with a Mobility roll. I think the rule therefore works fine. Want to crawl up a hill? Better pass a Mobility check. If you failed, then you didn't make it this action. Can try again each action until you do.