Actually, the rules detail almost exactly what the other player did (unfortunately in an example rather than spelling out the process):
http://help.yahoo.com/help/us/football/ ... es-14.html
3. If you pick up a player, but later realize you did not want him on your team, you may immediately waive him. However, you can only claim and waive the same player two times every 24 hours
This could have been written more clearly, but it is right there. Again I will ask: What did the other owner do to deserve losing the player? He picked him up legally. You missed the boat. Too bad.
If you want to bring it to Yahoo's attention that the recent activity page should reflect this activity correctly, fine, but there is nothing you can do in this particular case except to accept it and move on.
I am so smart. S-M-R-T