I was being facetious.
There are several possibilities here...
1) Sandeep truly intended for heat-seekers not to home in on hidden ships. But this seems counterintuitive.
2) Sandeep might have said "Missiles shouldn't home in on hidden ships", meaning aspect seekers (since they can't lock), and it was misapplied to heat-seekers too.
3) This was during FS1 development, not FS2, so they didn't need to wonder about stealth. Since they didn't apply it to stealth, maybe they forgot, or maybe they intended that heat-seekers
should home in on stealth. And I assume stealth is more powerful than hidden sensors (it seems obvious).
4) During the SOC mission where you look for Snipes, they specifically advise you to take heat-seekers to deal with sporadic targeting.
If there's a consensus that this should be changed, I'll change it. It just needs to be commented out.