Here's how I would have dealt with it:
"I'm glad to see you're concerned about protecting our facility. Is your concern that the bike might damage the building, or that I might leave it in a location that creates a danger? I'd be happy for us to walk together to show you where I park it."
During the walk, I would say: "One of the benefits of working here is that it's a friendly location for bike commuting. Our company values the health of its employees and also encourages alternative transportation."
And to finish: "Here's where I keep it parked safely so as to not be in anyone's way or damage the walls. We're glad that the building management knows that we take pride in this facility and are willing to work with us. I guess with today's high commercial vacancy rates, they'll do whatever it takes to keep tenants like us...."