most importantly, don't even think I'm trying to say Kupp should be returning punts. NOT AT ALL.
I'm speculating that in that particular situation where the punt is going to hang and you just want the best hands to field it I don't think having Kupp back there is a foolish idea. Nor is having Kupp back there in that situation any disrespect for Tutu or Funk's ability to return punts. Kupp is elite.
I don't know what McVay had in mind... planning on using Kupp to return all punts? I suppose that's possible, but I don't think that's the case.... because having Kupp back there to field a near 'sure' fair catch, (if possible), is a logical strategic choice IMHO - and not counter to a main plan of punt returns in which Tutu or Funk will be back there.
As specialized as McVay is, (every possible chess piece in the precise right position), the above scenario is quite logical.