He's not lying. Most of them don't even know why they hate him, and have gone as far as wishing rape on his 10 year old daughter.
I don't know about the wishing rape part - those are the worst type of fans - but people hate Roman because they continue to force-feed him as the next guy. Roman been in four (counting this next one) wrestlemania main events, like five top 5 placings in the rumble (won two), won the world title three times - including giving him the go over Vince to get the crowd pop. He's beaten Triple H, Undertaker, Cena and next is Brock all while not being a "crowd favorite." That's just a ton of investment for someone the smark crowd doesn't like. Meanwhile, you got guys like Balor, Rollins, Braun, etc who all go down to his move most of the time.
I'm just laying out what I think and see. Personally, I'm fine with Roman. I actually think he should go a year to 14 months with the belt like Lesnar did. He's gotten much better in-ring over the last 18 months and can even carry some guys in matches, though he still finishes people off with his move.