You are right for raids. However, in wars if you have several Guin teams in a sea of yellow tanks, you may not have a lot of purple heroes to spare. In that case, Cheshire could be part of a 3-1-1 or some such arrangement as a lone purple. What we don’t know is if the hero shift is persistent if you don’t manage to finish the team.
For super teams I would not use Cheshire. We have the misfortune to meet Crystal Palace in war right now, and they have 24 or so Guins but also tons of Gravemaker, Kageburado, Yunan, Alasie, Hel, etc. 4* die easily and even if you rearrange these teams you will still get trashed.
I was excited by Cheshire when I heard about him. I still am and I still want to level him, but you are right that for many he will have limited use. He has a cool avatar though!