Those are fairly big wattles for 9 weeks old, even in a non bearded Silkie I think.
The straight comb.. is incorrect which stinks since that's decent comb/wattle color for a white hatchery Silkie. Many are red instead even if they are lucky enough to get a walnut comb. Are the others also non bearded? Bearding gene inhibits wattle size.
At 9 week old.. best indicator might be behavior. Gender feathers aren't coming in yet on the saddle and the crest still has a ways to go to achieve their final form.
Thing is.. even hatched at the same time from the same parents.. they may get their hormones at different rates. This one may just be a tad slower than the other obvious boys.
I bred Silkies for a while... they were some of my least favorite roosters. They don't bring a lot to the table for the ladies either.. all my hens preferred large fowl roosters if given a choice. Sure, they're cute.. but first generation crosses will be hard feathered. Crossed back to silkie feathered will produce a percentage of Silkie feathered offspring. They're not bringing anything to the table as far egg production size or quantity. They're not the brightest color in the crayola box wit wise. They aren't adding or even maintaining carcass size if you happen to send extra boys to freezer camp. They do dress just fine for the table though, don't get me wrong. For me as a keeper.. I learned through this process that I don't prefer 5 toed birds. I have kept a stag pen since I grow out all my boys before selecting breeders. The Silkies did just fine holding their own and sometimes even putting Marans, Sussex, Ameraucana, and other large fowl boys on the run.. Sometimes it's not the size of the chicken in the fight but the fight in the chicken. Silkies are the master of sneak attack.. broody mamas are funny.. they have learned that very often if you surprise the opponent and get them on the run they choose flight over fight... sometimes it backfires but it works surprisingly often! When I did keep Silkie boys in a pen of their own they too often took turns mounting and essentially mating each other.. I'm sure it was a sign of dominance.. but the do go until they finish making their deposit. In other words.. stag pens/cock flock do have their antics. Depending on YOUR set up and the demeanor of YOUR boys, plus your resources like space, feed, etc.. it can be very manageable IF you truly wanted to keep them as pets. I have kept stag pens both in or out of site of the hens and it had zero impact on antics, boys will be boys! Another rooster on the other side of the fence.. is best with a visual barrier.. even boys that were getting along will fence fight when on opposite sides. My mature rooster free range with my hens had more concerns then fighting stags at the fence.. if they spent more time facing off with boys then escorting ladies then they weren't great roosters and would become subject to the stag pen themselves.
It sounds like you already have peace among you current flock.. and that is so key to being at peace too. Roosters that have already passed their awful teen phase, tolerate each other as co-flock guardians, treat the gals right, keeping them in line gently breaking up squabbles, No competitive over mating, and aren't human aggressive.. are worth their weight on gold!
I would suspect cockerel as well based on wattle size and age thinking it's a later bloomer than the brother. But how about a natural standing side pose?
Just for informational purposes and due to my serious over attention to detail most the time..
I will mention (for anyone that cares) chickens have
wattles and a duck tribe
waddles away from danger. English can be a seriously frustrating language at times. Even when I know the difference it still comes out of my fingers the wrong way sometimes. Just earlier today my fingers types what I wasn't even done thinking yet!
Here's to hoping for a great outcome!
