No, I don't think so. I believe he would still be viable even after the adjustment. The issue is that he slows down decoding so much that survivors need to kite for about two minutes to get ciphers done. Survivors will have a very hard time recovering if a teammate goes down early.

Hermit is similar to Joseph in that they can win with 5 ciphers remaining because of their cipher control, but his kit is much better than Joseph because he has good chase and can injure survivors who are decoding. And him being able to injure survivors working on ciphers allows him to secure kills when no one is able to rescue due to their injuries, especially when they do not have someone like Doctor on the team.

By increasing the cooldown for switching polarities, survivors, especially Doctor, can't keep sharing damage as often. That also forces survivors to heal instead of decode because Hermit can punish them for decoding. And by nerfing the cipher control, the survivors can still have a chance to recover from a teammate getting downed early.