Those other 3 officers (and the entire department) need to have skin in the game in that situation.
Yes retired officers should also be "reaping what they sow".
I don't know if would work in practice but there are multiple reasons to recommend it.
edit- just to be clear this would have to be negotiated as part of the union agreement and not something a court could just do.
The police pension funds work the same way. If the Minneapolis police pension fund was sued tomorrow and wiped out, the city still owes the police their pensions just the same as before. The money to pay those obligations has to come from somewhere. I suspect that it would come from the city.
It would absolutely have to be part of the negotiated agreement with the police unions and yes the retired officers of 2040 should be impacted.