Is this frame damaged?

Firstly you shouldn't trust all the advice you get from the Internet, but I'm still riding a frame that I got four years ago with similar damage.

(I'm suggesting tha my advice is the bit you shouldn't trust, not others)

Quite right, Sir.
Steel is a very forgiving and flexible material.
Just because a frame's been subject to forces beyond its plastic limit and deformed, doesn't mean it's dangerous; no holes, no cracks, no problem.

However, it is of no value, aesthetically and geometrically. I'd be after me cash back.