chess

1.d4 d5 2.e4 e6 

1900 said: “Instead of playing into a Blackmar-Diemer Gambit, I chose to transform the structure into a French Defense, with which I have more experience.” 

3.Be3

Harding calls this the Alapin-Diemer Gambit.

3…dxe4 

1900 said: “After 3.Be3, I didn’t know of any other option but to take the pawn.”

4.Nd2 

1900 said: “White makes Black play …Nf6 before pushing f3 so as to block the Black queen’s access to h4 for any potential checks.”

I think you might be placing too many reasons and thoughts into your opponent’s head. The fact is, 4.f3 is totally innocuous due to 4…e5! (actually, Black has several good moves after 4.f3. Watson recommends 4…Nh6 threatening ..Nf5), as the example below shows:

1.e4 e6 2.d4 d5 3.Be3 dxe4 4.f3 e5 5.dxe5 Qxd1+ 6.Kxd1 exf3 7.gxf3 Nc6 8.f4 Bf5 9.Nf3 0-0-0+ 10.Nbd2 Nb4 11.Ne1 Nd5 12.Ng2 Nh6 13.c4 Nxe3+ 14.Nxe3 Bb4, 0-1, Rafael Pita Romero Rodriguez (2112) – Humberto Pecorelli Garcia (2441), Poio 2003 [C01].