Generally, hiring one’s relative is illegal. Among the 27 relative designations listed in the federal law regarding nepotism and hiring, however, "grandson" is not mentioned.Legal text from the House of Representatives ethics manual follows.
So Moore, who makes a six-figure salary working for his grandmother, is just fine, ethics-wise, according to an ethics lawyer contacted by POLITICO.
I guess people in politics needed a term for obeying laws that prohibit certain self-serving abuses of power, and "ethics" was closest to hand. But I hope that they're still aware that one can obey these laws and still do grossly unethical things, in the sense of what's really right and wrong.