As I read it, the EPA is banning argon, not entirely (which would be ludicrous), but just from pesticides. That’s ludicrous too, but irrelevant. Argon is a noble gas—you can’t make it combine with anything, so it couldn’t possibly be part of a pesticide.
Neil Bartlett made several Argon compounds using Fluorine. (I think he should have won a Nobel Prize for this work.) It’s not easy to make Argon compounds, but it is possible.