Having worked in customer support - a lot - I don't place much stock in that kind of language. "Seeing the purchase on my account" can just as easily be "see that I redeemed the code from my purchase".
Not saying it is the case, just that it could be, until we get clarification from OP
Also, Steam can and definitely has allowed developers to revoke a license for various reasons. Usually related to fraud. But sometimes other reasons.
Here's the developer portal page that specifically mentions "ban or disable steam key" (which can be done even after the key is redeemed)