i understand your concern but I dont think you're status will get affected if your uncle has been found illegally working here in canada not unless you're the one arranged the job for him. In my personal opinion you have to sincerely talk to your Uncle to explain him how critical are the consequences if found working here illegally, it will jeopardize his future plans to move him permanently in the future and it will also be a reason for deportation.
I dont agree on you turning you're Uncle to the CBSA without even him engaging to anything illegal yet as this is same as already jumping to conclusion.