It is "legal" according to the National Electric code, however it would be up to the local inspector as to whether he alows it or not. If you're really concerned you could drill a small hole in the center of the stud just above the kitchen home run box and locate the wires on the other side of the stud. This would only require about 3 inches of slack (much less than going around the three gang box) and would definately pass inspection.

"jr" has a good idea. The home run in question already goes through an upper floor joist in line with the stud, so it's already "on the other side" coming from the panel, which means there will be plenty of slack to run it down the other side of the stud and come through above the single gang box.

The big question is whether I can drill a hole in the top plate of the wall. My joist drill won't fit in that space but my 18V drill/driver should be able to handle it... or I can just use a long auger bit.