I tend to disagree. It's a good list, he just didn't use much sense posting it here. The Destroyers can be deployed in such a way that your Long Fangs can't reach them, ie they could be harrassing your opposite flank, whereas he has Immortals in great enough numbers that with the Monolith and some cover, they're pretty safe from your heavy weapons also. I peronally consider the Space Wolves one of the tougher armies for the Necrons to go up against(any power armored combast-friendly list is a tough cookie to crack for the Necrons in my experience), and his army wouldn't do too badly if played correctly. You describe it as if he wouldn't have any tactics of his own. You'd take out his Destroyers first? You'd make him come to you? Ridiculous. As the Space Wolves, you'd be rushing to him in all likelihood, and he'd be using those Destroyers to harry you the whole way. You may well win, but don't act like it would be as easy as all that. Chances are that he can deny your Long Fangs a shot at your Destroyers(depends on the length of the board, though), and then he's killing an average of about 8 of your advancing Blood Fangs per turn, excluding any damage dealt by his Warriors or his Monolith, assuming his Monolith is using its teleportation to assist the WBB of his Immortals, which would probably be your next target if you were denied the Destroyers.
How would you suggest he change this list? By what I can see, it includes a great deal of firepower in a list of its points in the Destroyers and Immortals, giving it an offensive edge, while including a Monolith as well, to help with defense. I wouldn't call it mediocre. I agree that it was silly for him to post it for the mere sake of saying it was good, but we can tell him to do otherwise in the future.