The interests of the prime broker and hedge fund investors are often not aligned. e.g. Archegos - Goldman dumped the Viacom shares to save the bank from losses at the expense of Archegos.

Responsibility for a pension fund's risk sits with the pension fund.

Now if you're proposing that limiting a hedge fund's access to leverage by preventing banks from extending such leverage would overall de-risk the system thus providing a safer playing field for pension funds... possible, but you're attempting to derive causation in a complex system which begs the question of what unpredictable derivative effects come along with the change, the magnitude of those effects, and their net effect on safety.