“Afaik there was only one gadol who came out against this chiddush as the opposite of Avodas Hashem cvs, while the others did not,”
I’m not sure which dispute you are referring to. If you a referring to the Gra coming out against the Baal Hatanya, you’re wrong. As Sechel pointed out, he had many Chassidish opponents as well.
If you are referring to the modern status of Chabad, then you’re even more wrong. You think only 1 gadol was opposed to Chabad Meshichism? To whom to you refer? Because it could truly be anyone because EVERYONE opposed Meshichism.