if someone from Beis Shammai was invited to speak at an event, would the talmidim of Beis Hillel not come in protest?
You don’t have to agree with “the other group”‘s mehalech, but they are Jews too, they are talmidei chachamim too, and this event had nothing to do with the particular machlokes so why not have achdus? Why not put politics aside and make a kiddush Hashem and give kavod to Torah. (Unless you are considering a whole group of Jews to be apikorsim and therefore not b’chlal amisecha)