Until the travel restriction/rules are loosened, your brother cannot come validate his COPR along with your parents at the same time. He could still come (as a visitor) but will not be able to complete his landing unless your parents have become PR first.So there's no way my brother can come with my parents end of September?
Even though my MP emailed he was part of the application he will be fine.
I'd suggest following the latest IRCC/CBSA guideline - at the end of the day MP isn't the immigration expert and has no jurisdiction on the border policy.