A post earlier said the felons can't enter Canada,which is why PM Trudeau...

[LeftInTX]

4. Bush had a DUI and was admitted to Canada

President's Visit to Canada
Before a bilateral session at Parliament Hill, President George W. Bush and Canadian Prime Minister Paul Martin meet in the rotunda in Ottawa, Canada, Nov. 30, 2004.
https://georgewbush-whitehouse.archives.gov/infocus/canada-trip/photoessay/index.html

Before the 2000 election
DUI Stops Bush From Freely Entering Canada
https://abcnews.go.com/International/story?id=82199&page=1

However, as Head of State, they probably asked him, "Are you planning to drive?" He probably had to show some proof that he would have a driver.
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Although "Head of State" is probably not mentioned in their laws, I think the "spirit" of these laws are to avoid having felons roaming lose committing crimes in their country (countries) and drunk drivers driving in their country (countries). Even though he's a convicted felon, I highly doubt that Trump has an intention of committing a crime while visiting. However, I wonder if they could use this to avoid a waiver if they didn't want to "deal with him"? (I kinda doubt it)