He did not fail. Satan himself, with the koach of his Torah, came to his rescue.
Even at the onset, he wasn’t contradicting any Torah idea, he was just mislotzez bovrei avera. Whereas in the other case she was ridiculing a Torah idea. Whether she did or did not actually sin (don’t recall the inyan right now), that’s not the issues. But it wasn’t her Torah to the rescue.
But there’s another issue here. Sometimes HaShem sends an insurmountable temptation for reason known only to Him. Sometimes we too understand a bit. That’s what happened at the story of Yehudah and Tamer. He didn’t have any ‘shaychus’, connection to that episode. So HaShem turned up the heat. He motivated Yehuda’s senses and lusts just for that outcome. SO SAYS THE MEDRASH!
That’s exactly what happened at this Tanna’s ‘test’. ??? ??? ?????, when he’s given the go-ahead, we can be assured he’s doing it with all his capabilities. So I don’t think it was a test (like Rav Amram Chasidah), rather just to prove a point (not to be mislotzez bovrei avera).