How can it be mitigated? I can't think of a single idea. For future missions, sure, but this one?
Of course you can't predict single strikes, but maybe you can create a statistical model which direction strikes are most likely to come from, and prefer observations that point the telescope in the least dangerous orientations. Maybe there's even some seasonality to it due to interactions with the moon or with other planets, and you can just schedule observations in a particular way that reduces risk.
If there were any dangers obvious enough to detect from here, that destructive, we already wouldn’t be using that point since the mission is expensive and long-lasting enough that a statistical approach to protection would fail too quickly. (The suggestion made me think of “gun kata” in Wimmer’s Equilibrium which had the same problem, given the performance ratios stated in the opening monologue.)
The primary mitigation is to use predictions of larger events, such as meteor showers, and move the observatory to an orientation that reduces the risk of damage.