Sure it is. They have to accept they may suffer for it financially though, depending upon the circumstances. They have to accept that their reputation is impacted. On the other hand, some quits are completely justified and nobody will hold it agains tthem at all.
He'd already been put in check, and check-mate was coming. And, you don't know how Loma's punches were affecting Walters, Gan. Some fights play to the end and force their opponent to check mate them, but if Walters knew what was coming and chose to resign, then that's his call to make. Doesn't detract from Loma's brilliance and really only adds to it, imo.
Walters quit before he even started to fight. The fight was an extension of his mindset. That was an act of cowardice that I will never forgive or forget. Fk Walters. Now, the most noble gesture of defeat to me was made by Morales when he quit in the Pac fight. No shame in that surrender.