Yes, there is an online/phone tip line you can write to: https://bwl-lsf.cbsa-asfc.cloud-nuage.canada.ca/tip-sub-en.html
That said, they may still have to let him in if not convicted of anything or nothing that holds up to reasonable grounds for refusal. And the supporters could always write to the Minister involved, asking for them to intervene for his entry.
My response in another thread: https://lemmy.ca/comment/15484025