I suppose it is a bit of a question of priorities.
Putting myself in Rocky's shoes, it seems like that decision is probably based on two facts.
1) It appears like, thanks to the good work of Marvin and Null, Chris' person and property are not in clear and present danger from these people.
2) This incident provides pretty good evidence that Chris is not capable of taking proper care of himself. And that given Barb's state and everyone else's distance from Chris on a day to day basis, noone is in a position to supervise him sufficiently going into the future. So Chris' person and property are vulnerable in the medium term future.
If you take these together, you could come to the conclusion that getting some better level of supervision for Chris is more important and a higher priority than seeking justice for this incident.
But where I definitely agree with your point is that that doesn't mean that seeking justice should receive zero priority. If nothing else, it should help Chris at least partially recover money that is rightfully his.