Discussion of mumarim donning tefilin at chabad houses is noreshkeit. Most people whom chabad addresses are tinokos shenishba.
I once encountered someone who claimed to be an apikoires – learned when he was young and based on some interactions we had, became nostalgic for some learning. I first sent him to a litvishe rov, who said – you can come to the class on the condition that you’ll stay quiet. This did not work. Then, I sent him to chabad shaliach who spent some time discussing their differing worldviews without any problem.