Silkies are supposed to have a comb that looks like a walnut, which usually involves both the rose comb gene and the pea comb gene. Single comb is genetically not-rose and not-pea, and is recessive. So the parents could be carrying the genes to produce a single comb chick, even though they do not show those genes. (The chick's comb looks like pea to me, but I know it's easy to be wrong when looking at a picture of a young chick. Pea would just require both parents to carry the not-rose gene.)
For the color, my short answer is:
Dominant and recessive genes can do funny things sometimes.
Longer answer for how I think the genetics worked to get this result:
I think the Satin is Paint. That is a chicken with the genes for all-black feathers, and one copy of the gene for Dominant White. Dominant White changes black to white, but when the chicken only has one copy of the gene, it lets some black bits show through.
The Satin would have passed the genes for all-black to this chick, but not the gene for Dominant White.
The Silkie looks white, but white silkies often have a gene called recessive white. When the chicken has two copies of that gene, it looks white, no matter what other genes it has that would normally affect color. But a chicken with only one copy of the recessive white gene will not look white. So when the chick got one copy of the recessive white gene from the Silkie, it did not get that gene from the Satin. This means it is not white, and instead it can show other colors (like lots of black.)
