I'm not questioning the OP, but it just seems odd. The aisle on the upper deck is a lot wider than those on the lower deck. I don't think I would have any problem getting past another passenger (and I'm far from skinny!). It sounds like the crew member was going out of his way to be confrontational. Which is not a trait I have encountered in any other BA pilots. Maybe he was just having a very bad day, but that's still no excuse. No harm in feeding back to BA.