Rav Eliashev paskened that it can only be reported if there is raglayim la’davar. (A shaila needs to first be asked whether the case reaches raglayim la’davar.) The reason it needs to be reported in a case of raglayim la’davar is because of community safety in preventing the perpetrator from continuing his offensive and destructive behavior. If, as you say, it is certain he will not (or even cannot) continue engaging in his behavior, it seems the halachic reasoning permitting it being reported no longer exists and thus it cannot be done.
To reiterate, the reason halacha permits the reporting is not to punish but rather to prevent the behavior from reoccurring.