It stands to reason that, new to the area and a confirmed vegan, BK might enquire of the MA's Greek whether they are truly vegan. No contact, dedicated pans, etc.
Now Mad Greek personnel were pointed that BK has never been served... two of their employees are dead, unable to recall whether they encountered BK.
I think it's entirely possible BK lurked at the Mad Greek, if not inside, outside. In the lot, waiting for waitresses. I think BK encountered X or M or X & M at the Mad Greek, even asking his awkward (creepy) question, "where do you live?" And following the likely brush-off (he would see it as rejection, women see it as self-protection, spidey sense), how easy for him to tail her home....
Even if a waitress where friendly about it, he'd probably perceive that wrong too IMO.
I'm curious about those twelve trips into Moscow... do any align with closing time at the Mad Greek? M or X might have had a stalker without ever even knowing...
There's always a nexus. IMO it's going to be the Mad Greek, and the nighttime road prowler following a waitress home....
JMO