Here's the issue with the 'if Trump knew there was going to be election fraud/voter fraud, why didn't he pre-empt it and deal with things beforehand' argument; it ignores he did not have the authority to do much of anything.It's always with zee Germans!
I think some folks may be having a lark here
Though with the amount of time he had to prepare I'm surprised Trump didn't have something in place to prevent some of these problems. I hope he did have something but would need some solid evidence from a court for this.
The power to create/alter voting laws rests with each state legislature, and the only power in DC that can actually do anything meaningful about state voting laws is SCOTUS.