My ex had a argument with our son but I am not going to defend my ex.
Do you want to keep your son from seeing your ex?
No. I don't want to do that to my child.
It seems like your ex doesn't have tact. It's not cool for a parent to start arguments with a kid.
That's why I'm not going to step in. It's best to leave him alone.
If the argument gets to heated I would recommend you step in. You don't want to get out of hand and have more issues arise from it.