I guessed walnut mainly because he's got feathers in it. I have yet to see any combs besides walnut that have those tiny feathers in the flesh
Walnut genetically has both rose and pea comb genes, so I wasn't meaning to rule that out as an option! Just that the rose comb gene causes a widening of the comb area, more so than what happens with other comb genes, so he assuredly at least has a rose comb gene.
As far as feathering on the comb like that, you could be right in it being a strong indicator of that being a walnut comb. I don't have a whole lot of experience with walnut-combed breeds or feathering in the comb area, so I didn't even notice that or take it into account.
The front hen on the bottom is likely his mama
I agree with this as well!