Private Businesses are to be treated like someone's home you're a guest in. Period.
Vape until asked not to, then respectfully apologize if a situation comes up. Pretty easy method. Also, the owner of your local Santa Monica vape shop may not know all of the rules put forth by all local businesses in the area. If you're feeling extra polite, ask before you vape. The fact that nobody was in the establishment holds 0 water (or ml of juice

) to the rule set forth by the bouncer or the owner. If I were you, I would go to the local market and get yourself a potato and a pound of ground beef. Much cheaper method to getting your burger and fries fix on. I could spend that 30 bucks on a new mod and have myself a 1/2 lb monster burger with some oven baked fries...
As a rule of thumb, be wary of asking opinions on a situation when you are on the internet; you never will enjoy the outcome. This thread is a poster-child for that exact fact.