in.tftpd runs as root from inetd, even though the man page says
that the program should run with the least privileged account and the
files have to be world readable. So it should be safe to
run in.tftpd as nobody (works for me).
(Note! I didn't investigate if in.tftpd drops priviledges if run as root)

-Jarno

PS. I changed the tftp line in /etc/inetd.conf to this:
tftp   dgram   udp     wait    nobody  /usr/sbin/tcpd  in.tftpd
                                ^^^