Other regionals have similar provisions. It's good for pilots...

If they ever find themselves in need of a job, they can come back, suck up FO pay for a couple or few years and then be back at six figures.

Especially good for guys who got stuck due to industry dynamics and now cannot afford to risk going to a major and flunking out. This allows/enables those folks to attempt to move on without risking financial catastrophe.

Good for the company because it encourages senior (ie expensive) pilots to move one.

I would even take it one step further...since the whole point of the regional system for most pilots is (or was originally) to get experience and move on, I would allow pilots to return with seniority for 4-6 months. That way there is no downside to attempting to move to a major. Kind of like insurance, small cost to the group as a whole and very few folks would ever need to exercise that option, but if YOU happened to be that guy who the sim instructor didn't like the part of your hair...