If I found our all the details to his DUI, worse case could he request special permission to enter Canada and then apply for TRP if they allow him?
"
Coming to or remaining in Canada without approval of rehabilitation
If you need to come to Canada but cannot apply for rehabilitation because five (5) years have not passed since the end of the sentence imposed or you are not eligible to apply for a record suspension (formerly a pardon) for convictions in Canada, you may request special permission to enter or remain in Canada. To do this, complete the
Application for Criminal Rehabilitation (IMM 1444) (PDF, 1.18MB) and make sure you check the box that states “For Information Only”. Attach the documents outlined in the
Document Checklist."
^ just found this info off of canada.ca