Makes sense. Except I don't think Ubisoft would purposely make a game bad for any reason. (This is not to be confused with graphics downgrades. That's more to do with marketing)
Ubisoft just doesn't really care enough to make any of their games very good. They spend little effort on the Wii U version of AC or Watch Dogs, and they sell poorly as a result.
So, I guess your theory is technically correct. But Ubisoft doesn't make Wii U games intentionally bad to "prove a point" or to create an excuse to not make games for it... Rather, Ubisoft just doesn't put any effort into making their Wii U ports any good, and they sell poorly due to Ubisoft's laziness, which makes them think the Wii U isn't worth investing in, and you can already see the negative feedback loop this creates.
"Never argue with stupid people. They will drag you down to their level and then beat you with experience."
-Samuel Clemens
