its not fixed.
It is fixed for the claimed keypairs.
the problem with quadratics /malleability is that malicious people will use it to do mallicious things.
unless mallicious people CANNOT do it. then its not fixed.
You can't harm the network with sigops at 1 MB. Malleability is another matter. This is why everyone should strongly support switching over to Segwit keypairs and implement a stronger control for native keys.