Hi,
As you've discovered, the audience here is generally technically astute, but also deeply unforgiving when it comes to even a whiff of marketing over substance. On a bad day I'm as guilty of this as anyone.
Your idea to use the waste heat from a computer for something useful, in preference to simply generating heat with a resistor, is fine. I don't think anyone's questioning that principle. For an audience with a strictly electronics (but not thermodynamics) background, it might do you no harm to explain why running a heat source at a higher temperature can be a good thing when it comes to making use of that heat elsewhere.
Given that you obviously understand this already, you shot yourself in the foot when you mentioned Solar Roadways in your campaign. That project was the poster child for marketing over feasibility. Guilt by association, I'm afraid.
If you want to win over a technical audience, you need to explain, quantitatively, what your product actually does and how it might be useful. A simple explanation about its power consumption, MIPS per Watt, operating temperature, and the method for ultimately extracting the heat produced and making use of it, would go a long way. Above all, you just need to demonstrate that you have a strong understanding of the physics, and that you're not trying to do something for which the numbers simply don't add up.
A purposely inefficient computer would be a bad idea... no better than a laptop plus a bar heater. One which is just as good in terms of MIPS per Watt as any other server, but capable of running at a high temperature and providing a means to make good use of the heat that would otherwise be wasted, is potentially quite a good one.
I still think you should use a standard desktop CPU and make coffee with it, though!