Nah, he doesn't need them. In fact, he doesn't neither need that jacket, and that shirt, and those socks, and those shoes.
I wonder if брюки is related to the antiquated English word "breeches" for pants...
Possibly. The Dutch word is actually 'broek' (pronounce: brook). The 'ch' often changes to 'k' (Both in writing in and pronunciation) and vice versa. Dutch and English are very closely related.
Right, just as in English, брюки is always used in plural, you can't have a single pant or trouser (or брюка).
Why is "he needs the pants" not accepted? Would that be "Ему нужны ети брюки"?