It could be a roo, I was just saying i thought it was hen, because of my past experiences with RIRs. All of mine matured fast. I do see why you said roo, especially with its thick legs.I would say it's a roo based on comb/wattle development and those huge legs. At just 7 weeks of age you won't yet see any saddle or hackle feathers just yet. BUT, I have on occasion had hens who matured faster then others and showed more comb/wattle earlier. So if this bird is destined to the hatchet if it's a roo you might give it some time to be sure it's a he.