According to Arminian apologist Josh Thibodaux:
“The term ‘author‘ as employed by Arminians/Synergists in this case, is used in an originative sense to describe where the evil ultimately arose from. If we can identify, ‘whose idea was this?’, then we’ve found the author…[Originate] Thought it up, dreamed it up, came up with the idea apart from anything external…I would say He allowed it contingent upon the creatures’ wills, but didn’t dream up their evil schemes Himself.”
This fails to draw a couple of elementary distinctions:
i) It fails to distinguish between evil ideas and ideas of evil. There is nothing intrinsically evil in thinking about evil deeds.
For example, an FBI profiler from BAU will try to get inside the mind of a serial killer. In so doing, the profiler will contemplate “evil schemes.”
ii) What is more, the profiler will try to anticipate the serial killer’s next move. As such, he will “dream up” “evil schemes” in his effort to stay one step ahead of the killer. The profiler came up with this idea on his own. The killer didn’t plant that idea in his mind. Rather, the profiler “originated” this idea in his effort to forestall that very eventuality.
So there’s nothing intrinsically evil about entertaining or even originating the notion of an evil scheme.