Since we can’t post urls here. Google rabbi Yitzchok schochet response to RCA resolution that was published in Jewish chronicle.
Basically he says the Rebbe never started the messianic mission. The messianic mission as told by pasukim chazal and Rambam is building the bais hamikdosh and kibutz galios etc. A campaign to publicize Moshiach’s coming and getting ready for Moshiach is by no stretch of the imagination considered starting a messianic mission unless one is a crack pot professor and riding a tide of infighting and open hostility towards Chabad etc