Pretty sure bet they are much much more mature than the 9 week olds, if they were anywhere close to the age of the 9 week olds they likely wouldn't be identified as "roosters".
To the op take Ole Grey Mare's advice and separate ASAP before some of the chicks are seriously injured or killed.
Eh, to folks who use the appropriate terms (pullet/cockerel & hen/rooster) that is a natural assumption - however, we all know what ***-uming does, and I have seen plenty of folks refer to males as young as a few weeks as roosters in posts here on BYC, so I've simply adopted the ask and be sure policy.