I might be wrong but for a songwriter like Mark it doesn't matter the song or if it's well played or not, coming across a kid who was born way after DS's last concert and knows his music must be a good feeling.
You say it as if Mark is a rising star who just started playing lol. Of course he have seen people from 0 to 100 playing his music, it's just that I don't understand the guy and his choice of song. Sultans? Come on...
I would say his signature song and one his most famous riffs, along with MFN. Even Mark has given a name to it! I wouldn't say any of his solo work has a famous riff or even recognisable part he could play. Ease up a bit!
I can't ease up when it comes to SOS, I'm sorry
I dare say that kid's parents are probably younger than Sultans...
All this doesn't justify the banality of playing signature songs in front of the artists themselves.
If I were the artist, I'd smash the guitar against the head of the genius who thought that it would be nice to play it for me.