In the absence of his queen, Black has a problem with the e5-pawn and with the a4-a5 threat.
2...Bg4 3.a5 Nc8 4.Rc1 Bxf3?! 5.gxf3 Ne7 6.Nd5! Nc6 7.Nxf6+ gxf6 8.Rd7! Rab8 9.Kf2
Gaining some space on the kingside, before Black achieves the same thing by 1...h5.