You have to understand how programmers think.
If it works as intended by the programmer, then it is technically not bugged.
In this case, for simplicity and probably implementation costs ED chose to implement FLIR as a color filter. That is (in simplified terms), the shade of green that most ground vehicles sport is mapped to white, everything that is not that shade of green is mapped to black (obviously with transition in between and the ability to switch polarity for BHOT).
Everything that has the same color as most ground vehicles will appear hot for that matter. That in itself is not a bug, but a side effect of the simplified design.
To truly emulate FLIR, one would have to retexture every 3d object in the game for the infrared spectrum. You can imagine what a herculean task that is.
The next chance where this *might* happen is possibly with the F-18, as it also features FLIR. Looking at the A-10s product lifecycle, it is simply too much to ask from ED to squeeze so much development effort into a product that is now on "extended support". The F-18 on the other hand is a new product and as such, has much more potential to actually recoup such a development effort.
To cut to the chase: Don't expect ED to retrofit a better FLIR render method inside the A-10C project. If you want to campaign, ask them to develop it for the F-18 and retrofit it to the A-10. That has at least a nonzero chance of success.