deemed rehabilitated for old US misdemeanors?

[immcrim]

I understand you can be 'deemed rehabilitated' even if excludable for very old US misdmeanors. Someone-- a USC- has asked me about visiting Canada with:

a misdemeanor shoplifting conviction that is about 35 years old; and
a criminal trespass (arising from a nonviolent sit-in-- "remain without permission") about 16 years old.

Could such a person be found inadmissible, or alternately deemed rehabilitated at the border?
I've looked at the Canadian Immigration website material and it's helpful but only in a general sort of way.

Any informed responses would be appreciated. I usually advise about US removal grounds, not Canadian ones

Thanks.

IMMCRIMM