It isn’t strange to use your non-dominant hand for things, no. Maybe most people do lean toward using their dominant hand for everyday tasks, but I think it’s a matter of habit for most things. “Non-dominant” doesn’t mean “nearly useless”.
I would say it is a bit strange for your friends to pay a lot of attention to which hand you use to unlock doors.
https://www.bbc.com/news/technology-65789916
Apparently it was a story told by an Air Force colonel at an aeronautics conference, who later retracted it.