It's in the rulebook that any character with the stubborn rule will give that rule to any unit they are in. Hence why High Elf players dump Korhil into Phoenix Guard all the time rather than with his own White Lions.
And as to the debate of if horde saurus are worth it, I would say normally no. Though I have done it to great success, it requires a slightly different play style and makes terrain and positioning far more important. Against dwarves, empire, chaos warrs I think it is a bad move. But, give them frenzy banner and spears and you are looking at 4 deep attacks with potential for 30+ in the front row alone. It works best against other horde-centric armies as the width is not as much a factor, 10 Gobbos/Skaven are 200 wide and 10 saurus 250, so you would get all of your attacks in, all while hiding that skink bsb to the far side. They coming at your flank? Combat reform that little dude to the other side. Both flanks? You should be protected by something on one of them (TG, Skrox, Steg, a juniper tree...I dunno, plan ahead).