Puma is not a hard counter to t70 imo. It is still very fragile especially to oorah plus snare, penals with at, guards with at. Add the fact that t70 penetrates it too. There are also at guns. I don't see a reason why puma should come later than t70. Especially because it doesn't give ostheer anything in terms of anty infantry.
GCS2's Mobidef meta is why.