To get that out of the way: I don't like Metallica (particularly out of historic reasons but also because of Ulrich/Hammet). They do deserve some merits in the textbook of modern music history, though. And, most of all, they can obviously just do what they think they should do.
Whatever, what I find to be quite stunning is that people are getting all up in arms about that particular "Lux Æterna" solo. Seriously, for quite some reasons, that solo a) is one of Hammet's better ones and b) works just fine within the song. And remember: I'm saying that as someone who doesn't like Metallica (and Hammet as a guitar player usually even less). So WTF?
Then, as it was linked in the OP's article, I watched this dude's take here:
For REAL? His main criticism is that Hammet's solo has a pretty clear 2-bar oriented form. What? Sure, it might not be the most lyrical way to tell a musical fairytale with your oh-so-great soloing, yet, it's absolutely a very well working structure, especially in that short amount of time. And at least it actually HAS a structure (which plenty of mindless noodlers manage to miss completely, regardless of whatever technical stunts they're able to pull off).
And as if that wasn't enough, he's coming up with his own solo. Which actually left me speechless for a moment. When he said it'd be coming I was like "ok, dude certainly is a monster player and my jaw will drop for sure". But WTF did he come up with? That's got to be *the* perfect prove of someone not understanding what Metallica is about at all. Even I - remember, a dedicated non-fan - have a vastly better understanding. Yeah, guy has chops, but that solo is just as non-fitting as it gets in a Metallica context. Woah...
Anyway, guess all I'm saying is that most people critizising Metallica just have no idea. And Hammet, as much as I generally don't like his playing, has all the rights in the world to laugh his @ss off about those folks.