That sounds similar to a FATE character evolution mechanism, where you do not gain more skill points but can shuffle some around.
The main issue relative to RM standard rules is that RM does not handle specialised on-the-job learning particularly well. Basically, in order to learn something, you must gain a level (or more). Which is, as you said, not always believable.
I must admit that I would have a bit of trouble saying "well, you can re-develop a couple of levels, forgetting the ranks you gained (and potentially used) and developing new ones".
I'd rather simply give ranks in skills the characters are supposed to learn because they have to. This can apply to survival skills like in your example, but can also apply to very specific learning (say, the characters are stuck in a house somewhere and are given crash courses in the geography, history, social structures and languages of a region they have never visited, because they will be sent there afterwards). Giving a level or two seems odd. Giving ranks in the specific skills they are taught seems more reasonable.
In the end, the more situations like this one you face, the more you realise that you've switched to another game paradigm, one less like RM or D&D, where experience is generic and comes mainly from adventuring because that's what characters are supposed to do, and more like Bushido, where experience is specific and comes mainly from training and learning, with adventure experience being the icing on the cake, RQ being in the middle of the road (experience is specific, but characters develop mainly by actual use of skills during play).
But to come back to what you suggest, I'm not sure I like it, probably because it clashes too much with my view of what a level is, and because I think you learn things more quickly than you forget them. It seems a bit too much like trying to shoehorn a non-level based development situation in a level based development system. I'd rather simply go around level-based development in this case (and have actually did it in the past).