No, he don't crush. It's 100% possible to tank both phases. Just if you are min-maxing and have both paladin and warrior in best gear available, pick warrior.
It's better to have 2 tanks during air phase anyway. You have to pick up and hold 20+ skeletons spawning all over the place killing your healers.
Be ready for Ironshields and max debuffs on him, 14k hits are nasty. He has pretty slow attack speed tho, so it's healable.
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Fiorina / <Black Division> / EU-Drak'Thul
http://eu.wowarmory.com/character-sheet.xml?r=Drak%27thul&n=Fiorina