Core would not because they're all convinced we must have segwit before increasing the block size to prevent a quadratic scaling sigop DDoS happening... though segwit doesn't change the sigops included in regular transactions, it only makes segwit transactions scale linearly which is why the blocksize increase proposal is still not on the hard roadmap for core as is. If block generation is biased against heavy sigop transactions in the core code (this does not need a consensus change, soft fork or hard fork) then pool operators would have to consciously try and include heavy sigop transactions intentionally in order to create a DDoS type block - would they do that? Always assume that if a malicious vector exists then someone will try and exploit it, though it would be very costly for a pool to risk slow block generation/orphanage by doing so.