I actually had need of such a ruse myself long years ago.
Sitting in our HS after school hangout waiting for friends. BCP=Before Cell Phones.
This guy takes a seat in the booth opposite me and starts talking and asking personal questions including, why was I alone there?
I told him I was with my boyfriend. He said I lied and asked where was he then?
I happened to look over at the game spot near the bar and there was a really large muscled tall guy playing one of the games with his friend.
Viable candidate. So, I pointed and said he's right over there.
Persistent little punk said, no he's not. Prove it.
So I got up , walked to the guy, introduced myself and explained my problem. The big guy, who looked like Tom Selleck of Magnum PI fame at the time, took my hand and started walking me back to my booth.
He was 6'8 and played football for a nearby high school.
Worked like a charm. Little guy left the booth and the restaurant.
RE : the OP scenario, if they were female I'd play along.
If male, not likely.
What's a man need a 5'3'' woman for protection for from someone following him?