Factotums are useless, don't do anything, Rogues have sneak attack, the tier system is dumb, no way are samurai worse than all the NPC classes, etc.
I don't see how he can think them to be useless. Unless you figure that spellcasting both arcane and divine is useless, or that having all skills as class skills is useless. Not to mention rogues are d6 HD instead of d8. I'll admit that I'm not a fan of the tier system because not everything should be about the numbers considering the game's supposed to be about role playing, and not how much damage you can efficiently dish out each round, and the samurai's still better than the warrior unless you're someone who thinks that any class that's limited to being one of the three lawfuls instead of chaotic or neutral makes them worse.
I don't know. Maybe he's looking at the 8+int being better than 6+int for skills. Or the fact that factotums have to spend inspiration points to do what everyone else can do too. Last time I checked a factotum could do sneak attack, just not for free. Maybe the trap sense, evasion, improved uncanny dodge, and the special abilities are the winning combination he's looking at? All-in-all, I don't think he's looked over the class too closely. They both have their merits, but the factotum is the true jack of all trades. The factotum isn't the best at everything, but he can do everything almost as good as everyone else. Give him the right feats, race, and PrC, and he might even do it better.