I personally have never had integration problems with my sweet roosters (other than with another cockerel/rooster). They have always been quick to make sure chicks, especially pullets and a new hen are ushered into the flock with as little drama as possible. That's their job.
Your rooster is being territorial. May I presume these are not broody hatched chicks but chicks you either incubated artificially or purchased from a feed store?
I personally have great roosters who are quick to integrate...but I tend to broody hatch, so the whole flock, while of course hazing the youngsters so they learn their manners, let them run amongst the flock. The rooster (both of mine) are quick to integrate the chicks.
Just tonight I had 6 of my 6 week old chicks burrow under the fence that divides my two coops and ended up in the opposite coop with a different rooster. All were roosting on the roosts quite contented with the rooster keeping a watchful eye on both. (Never mind this totally screwed with my "brown Barnevelder line" vs my "blue Cream Legbar line." (LOL). But the Barney rooster was fine with the CL chicks not his own.
So generally roosters *should* be quick to integrate new chicks, especially pullets.
However your boy sees these as interlopers. Keep showing the chicks to the flock with a fence in between to acclimate all, or at least free ranging with plenty of hiding places. Your boy *should* accept the pullets without question. Roosters *should* want to make sure the new girls are part of their flock. (Young cockerels are generally ignored until age of sexual maturity where they then can be chased away by the senior rooster).
So I would say while perhaps not entirely uncommon, with purchased or unfamiliar chicks, it is not showing the signs of a good rooster leader. I can't say if he will chill in time. Hopefully he will especially as he begins to see the chicks becoming pullets....any cockerels again could pose a problem. (I have to keep my roosters separate for the first year).
LofMc