No one expects the Danish Gambit

There used to be Grandmaster Openings (Nimzo, Semi-Slav, Sicilian Poisoned Pawn) and Club Openings (Scotch Gambit, Colle, Latvian Gambit). Then the lines became somewhat blurred e.g. Kasparov adopting the Scotch and the Evans Gambit, Nakamura playing 2.Qh5. But there were some lines that GM's didn't play (or cross). One of these lines was the Danish Gambit, at least until recently.

In the recent Moscow Open Yu Yangi decided to turn a Goring Gambit (a surprise in itself) into a line of the Danish Gambit, by offering the b2 pawn, instead of playing Nxc3. He then proceeded to successfully hack his 2550 rated opponent, in a manner fitting the choice of opening. However there is one question that nags me. Is the fact a GM has played the Danish means it is now sound, or is it simply a function of the number of GM's we now have?

Yu Yangyi (2607) - Jumabayev,R (2555) [C44]

Moscow Open E Moscow RUS (9), 06.02.2011

1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.c3 dxc3 5.Bc4 cxb2 6.Bxb2 Bb4+ 7.Nc3 d6 8.Qb3 Be6 9.Bxe6 fxe6 10.0-0 Qd7 11.Nd5 a5 12.Ng5 exd5 13.exd5 Ne5 14.Ne6 Nf6 15.a3 Bc5 16.Rae1 Kf7 17.Nxc5 dxc5 18.Rxe5 Rhe8 19.d6+ Kf8 20.Rxc5 Qxd6 21.a4 b6 22.Rf5 Re6 23.g4 h6 24.h4 Ke8 25.Rd1 Qe7 26.g5 hxg5 27.hxg5 Nh7 28.Ba3 Re1+ 29.Kh2 Qe6 30.Rxe1 1-0