Answering the 2nd part first, RICO is federal so no the AG would have to refer a complaint to the US DOJ (and we know who is the fox currently guarding that henhouse).
The second part is tricky too. RICO in shorthand is federal racketeering. Under RICO, a person who is a member of an enterprise that has committed any two of 35 crimes—27 federal crimes and 8 state crimes—within a 10-year period can be charged with racketeering. (wackypedia)
It would be a long shot to convict but I bet they could really put their butts in a sling. And I do believe that they could decertify the union, at least in Wisconsin.