I don't think it was shade. No one would PAY the person they're shading. I think Madonna just wanted to make a statement and poke fun at it. Shes been very open about her love and support for gaga and how shes obsessed with peace so why would she do this out of bitterness? If she never made the 'reductive' remark none of us would think this was shady.
I love Madonna's sense of humor about it all. I doubt Gaga's pressed about it too, I think her stans are trying real hard to be offended.
He probably doesn't know the specific details of it. Meaning he wasn't aware of it to begin with. That's what I got from how he said it.
Madonna would find a loophole to avoid paying Gaga a cent, but since the royalties would come from the venue, I don't know that it'd really matter that much to her.