Why you shouldnt play with randoms.

For some context I decided to join customs with a guy named aresVIP and some other guys. AresVIP and me where the high level guys and the other 2 were new. In the game he had to afk so he was going to crossroads with a very new player however decided to come to us instead by which time me and a fellow random teammate were on train tracks infront of gas station. He asked if any of us were on the railway to which my teammate said yes but he still shot at us however missing all his shots on us and killing the new player he was with somehow. A right rat. Then my teammate died to a scav behind gas station i then killed said scav and then my teammate asks if i was outside sprinting however i could not speak as he wouldnt of heared me as i had construciton happening outside and it would have ear raped (i told everyone in my team ill wiggle and spam cease fire to show its me) i went into gas station and he asked if it was me and my teammate who he killed in friendly fire says something along the lines of "yea hes muted" however he didnt listen and tried to kill me so i dropped him and this is his reaction. I'll repeat i did say i was going to mute and they all agreed to it saying its fine just wiggle etc. Was i in the wrong?