Erev Rav

Rashi mentions by Eleh Elokecha and shicheis amcha that it was mostly the erev rav who Moshe accepted or mikareved that made the problems. Perhaps this was Aharon’s thought process and mistake. He felt that they should not have been brought along was hastening along their split from the Yidden. And his mistake was that it also drew in some Yidden along the way.