It can be effective all you want. When millions write him in, Caplan is going to strike out. Which is fine by me
It isn't that simple.
9 States prohibit write-in voting for president. 34 states require a write-in candidate to file paperwork with the state often with a slate of electors who in turn maybe required to file with the state. As these documents often have specific requirements, I can see states rejecting the requisite paperwork.