yes, his work ethic will go back up to 20 if you try again and then rescind it.
in the olden days, it was possible that on your second try, he might take it. however, this was exploited by people who would try it 8,000 times and so at some point, WIS put in a fix, and to keep it simple, the fix guaranteed that if the player was unhappy on the previous try, he would be at least as unhappy on this try. or at least, that is how i understand it. so it sort of took away a 'feature' in a way, but i think the 'feature' logic was very poor (in the sense it wasn't really looking at things like, well 10 games have elapsed, maybe there's a sliver of hope now?, or whatever).
but yeah, go ahead and give it a shot. you will definitely not do any lasting harm by trying it again and taking it off when it doesn't work.