For what definition of "workable"?
For one to define "workable", one must understand the goals to be acheived.
The goals in this care are _not_
1) To get anybody to register their RC aircraft.
2) To get anybody to stop doing stupid things with RC aircraft.
3) To prevent accidents or damage when people do stupid things with RC aircraft.
The cry has gone up in Washington D.C. that "Something Must Be Done!".
And the goal is to have "Done Something".
Something has now been Done.
I'm sure Sir Humphrey could explain it better...
There is a slight possibility that purely by chance the "Something" might provide a new club with which to hit people who do something particularly stupid with an RC aircraft, but in most cases existing tort law probably provides a better one.