Operational Flight Program (OFP) 2 - or Suite 2 - was fielded for the A-10A, not the A-10C.
The A-10C wasn't created until fielding of the Suite 3 Precision Engagement (PE) OFP, which actually came AFTER Suite 4 was fielded for many A-10A's. True story.
The OFP modeled (kinda) by DCS has a TGP diamond in A-A mode when the TGP LOS is at boresight, however this is not simulated. As a crutch, you can certainly set the Depressible Pipper to 41 mils to approximate the boresight LOS.
However, if you have a bandit in sight, in the HUD FOV, why on Earth would you pull him to the Depressible Pipper in order to go heads-down and screw with the TGP when you should be BFMing the sonofabitch, driving to the AIM-9 WEZ, or pulling him to the EEGS/MRGS for a gunshot?
The white dot is called the Situational Awareness Cue. But in a practical application of the TGP in A-A mode, can you really see yourself staring down at a tiny white dot on a 5" MFCD while maneuvering your aircraft against a bandit who is WVR and trying to kill you? It's there as a crosscheck during low-workload periods, like medium-altitude sensor search, not A-A combat.
The TGP, as modeled in DCS, does not have a genuine A-A capability because certain characteristics are not simulated.