AITAH for not letting my husband change fantasy football rules mid-week?

My husband and I are in a fantasy football league with several friends, and he is the commissioner. For context, it is a very low-stakes league with a $20 buy-in, no trophy/punishments, and some people put in little to no effort over the season. My husband pays the most attention by far, watching games all weekend, listening to podcasts, and even paying for a website subscription to help him out. He's in two other leagues that are much more competitive and have higher stakes. I watch most games with him and I always make sure to set a good lineup, but he is definitely more invested in it than me. Ironically, I ended up winning last year, and he got last.

This week, Week 1, we play each other. Last night, McCaffery was announced late that he was out, and my husband had him on his starting lineup. All his players had already played (including his bench), and without him, it was 50/50 whether he would win our matchup. However, he was convinced that he should be able to drop a player from his bench, pick up his backup, and slot him into his starting lineup. Our league rules apparently didn't allow it (which made sense to me), and he got frustrated because it was allowed in his other leagues. He would've changed the rule himself right then, but he didn't have his computer and needed mine. It turned into a tantrum, and it kinda ruined date night, but AITAH for not letting him change the rule mid-week, with no league approval, to help win against me?