Further prophylaxis, against any checks along the g1-a7 diagonal and the first rank.
Preparing 2 Kg2, in order to avoid any surprises along the back rank, and put the king on a square of opposite colour to the black bishop.
The beginning of a flawed plan. More solid seems 4...b5 5.h5 Bxd4! 6.Rxd4 Qb6 , followed by ...Qe6.