I mean, I totally get why Margo is annoyed (about this, not her other outbursts). If some random stranger was creeping around outside of my apartment/office building and answering all my questions in cryptic non-answers, I'd probably get pretty irked and shout a sassy comeback like "talk to the hand!" or whatever the kids are saying these days.
BUT WHY WOULDN'T SHE FIND OUT HIS NAME?!?! Just for the sake of ending this loop of mystery man interaction/verbal beration of co-worker or loved one/complaining about planning her mother's wedding that we've been stuck in for months. Lather, rinse, repeat.