Escalating nonsense

I walked past 1 London Wall and saw two sculptures, which looked fantastic. I popped in to the lobby and, out of goodwill, found a security guard (not the one pictured in the background) and asked if it was ok to snap them. No, it wasn't, he said.
Strange decision, I thought, as it would do no harm. But, anyway... I said, ok, I'll just take a pic from outside.
This was meant as a closing nicety, not antagonistic.
However, again, he told me, no, I wouldn't. I calmly explained to him, yes, I would, as it's a public right of way and perfectly legal for me to take a picture in the street, but he became more stern.
As is evident, I got a picture, with the fear of being 'moved on'. Not the best at all, but wanted to publish it as small mark of victory.