Re: Really weird Continuity error. HUGE SPOILERS!
Maybe he just learned a thing or two from Kirk Prime over the decades and decided to make his hair look different and spark both conversations and jokes.
On the bright side, any Spock haircut from any era of any timeline looks more natural than the Kirk toupee.
Human instinct is pretty strong. You can't expect us to change overnight.
-Captain Jonathan Archer, 2151