It sounds like this is is still a legitimate transaction in your league, according to league rules. Some GMs think this type of business is within the rules, others think it's collusion/circumventing. Most people think it's a legitimate deal, but I can see how some people might want to gripe about it.
My suggestion if you want to avoid this in the future:
Make the rule - "A player claimed from the waiver wire must remain on the team that claimed that player for a minimum of one week before the claimed player can be traded."
This means a claimed player can't be flipped right away, but at least the player can still be a trading asset in the short-term as the GM would only have to wait a week to trade them.
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