You,
“Rav Ahron followed the Mishkinos Yaakov who does not accept shishim ribo as a criterion of a reshus harabbim at all.”
I am aware that Rav Ahron accepted the Mishkenos Yaakov regarding Mechitzos in opposing the Bais Efraiyim (as per his responsum in Mishnas R”A) , but where does he pasken like the Mishkenos Yaakov regarding Shishim Ribo?
That is going against all previous poskim, like Magen Avrohom, T”Z, and even the MB leHalacha.
Especially if there is a Tzuras Hapesach involved, many poskim uphold that its in any case (even with 600K) not a Reshus haRabim M’Doraisa and is only D’Rabonon that a Tzuras Hapesach won’t suffice…(see Shulchan Aruch Harav 364, Avnei Nezer CM 107)