Because, as a recently-excommunicated Tea Partier, Senator Paul is still irresistibly drawn to lost causes....
Where this support, and millions of dollars of financial backing, for Cuccinelli were in this race before now is anybody's guess. It's almost as if the GOP was too busy ripping itself apart to even bother contesting the Virginia gubernatorial race, which is now guaranteed to fall into the hands of Clinton fixer Terry MacAuliffe.
Hopefully the term-limited Bob McDonnell can continue the Virginia tradition of governors-turning-senators and take out Mark Warner next year. After all, MacAuliffe has to have somebody to beat in 2020.