LOL, great story! Personally, I would have flipped if I was grabbed on the arm...NO ONE touches me except my fiance' or a law officer. I would have ripped my arm away and screamed "DON"T <explitive> TOUCH ME". I've done that once in the past and the rent-a-cop jumped 5 feet in the air and nearly wet himself. I ALWAYS bring my bike into stores and I have never been hasstled. One person DID try to stop me at the Walmart once (I too despise Walmart but I also have to go there on occasion) but I just ignored the person and kept walking like I owned the place; that's always worked for me.
As for selling your bike at the store...give me a break. Like Walmart sells quality bikes. The only "name brand" bike they sell are Schwins, but I'm not sure their craptastic method of putting them together even qualifies it as a street legal bike in the first place. You aught to have told them "Don't worry, no one will mistake your **** bikes for my LBS bike" ;-)

-TPM