For me this isn't a Pallas's Gull and I think your friends were onto something with YLG.
If this was a Pallas's gull it would be a 1st winter/second calendar year.
If a YLGull it would have to be a 2nd winter/3cy (which is what I believe it is)
I have no direct experience with PG but I would expect one to show a more droopy bill than this bird, with a dark 'smudge' that is strongest towards the rear of the ear-covert area. This bird has the darkest markings concentrated immediately around the eye, with very little towards the rear. More importantly, where are those conspicuous sleepy white eye-crescents that are so characteristic of Pallas's Gull? ...and the dark hind-neck 'shawl' of that species (also mostly lacking).
The basal half of the bill here looks more yellowish to me than the pink I would expect to see on PG (though it's difficult to make a really accurate assessment from this image).
Finally, even an advanced second-calendar year PG should show some retained first generation (brown) tertials, yet this bird has fully replaced all of its tertials to grey feathers-another feature which rings alarm bells for Pallas's.
Therefore, for me this is not a Pallas's Gull at all but probably a 2nd winter/3cy YLG. I hesitate to be more certain as I don't see many YLG of this age in my part of the world...