Tyre Changing 4x4 Different Loads Front and Back

I have a VW Tiguan 4 Motion and went to my local Costco store and they said they are unable to install the Michelin Cross Climates because the other two tyres have a different load rating.

I was wondering whats the issue of doing this? I have full intention of going full cross climate but I’ll also ask to rotate the tyres so old ones move to the front and back ones have new ones installed.

Existing tyres are 235/50 19 V (99)
Cross Climates are 235/50 19 W (103)