I am playing few years strictly 1.Nf3 with the intention to play Reti Opening. In my last OTB game I experience Navara Gambit (from a Czech GM David Navara) in Reti Advanced variation:
[FEN " "]
1.Nf3 d5 2. c4 d4 3. b4 g5
Looking at it I made a conclusion not to take the pawn as White would be in not ideal position (playable though):
[FEN "Greedy variation"]
1.Nf3 d5 2. c4 d4 3. b4 g5 4. Nxg5 e5 5. d3 Bxb4+ 6. Bd2 Bxd2 7. Qxd2
So in order to avoid that situation I played 4. Qb3 and after 4. ... g4 I would simply take the d-pawn
[FEN ""]
1.Nf3 d5 2. c4 d4 3. b4 g5 4.Qb3 g4? 5. Nxd4 Qxd4 6. Bb2
So my game went like this
[FEN ""]
1.Nf3 d5 2. c4 d4 3. b4 g5 4.Qb3 Bg7 5. Nxg5 e5 6. d3 a5 ...
The result is not important for this question. I also played few variations in Navara gambit (with my friend) and it looks solid for White and Black (this is subjective opinion of ~1600elo player).
My question is: What would be the general strategic idea for 4.Qb3? Stockish 15 in 60 depth also suggests 4.g3 (as the ideal move ~+0.5) move what seem too passive in my eyes.
I appreciate any source, experience or idea.
Thanks!