I'm not aware of anyone who's made that accusation. Minnesota statute requires prosecutors, in any case that would require revocation, to inform the issuing sheriff, and repeats the background check annually to catch any that were missed, so the window between action and revocation is fairly small.
Still, that he had a valid carry permit doesn't prove that he didn't do something stupid. I'm wondering who his instructor was, because dealing with a a police stop is something that should be covered.
I ask because given his propensity to smoke pot, his permit was likely void upon receipt.
According to MN law, any use of a schedule I – V drug invalidates the permit, and in MN, marijuana is a schedule I drug.
The presence of weed, as well as having the pistol on display during a traffic stop, invalidate the permit.
Also, the coroner’s report shows his address as Ramsey county, not Hennepin, so have may have a third invalidation. MN Sheriff cannot publicly disclose if he notified them of change of address, so we may not have a definitive answer there.