This isn't really a bug or suggestion, just an observation to keep in mind.

The liquid fuel heating doesn't have scale_fluid_usage = true set, so it will try to consume as much fuel as it can whether or not it can use it, even ignoring the max temperature. It consumes 6 fluid per second, but only produces at most 40 MW of heat, regardless of fuel value.

This is an interesting limitation, except that Metal and Stars also adds liquid rocket, nuclear, and dark matter fuel, with fuel values of 11MJ, 133MJ, and 72MJ respectively. When fed with rocket fuel for example, the liquid fuel heating tower will still 40MW despite consuming 66MW of fuel, with dark matter and nuclear fuel being even more wasteful. As far as I'm aware, there's no way to throttle the fluid consumption of the towers, and they will either consume their full demand, or none.

After some testing, it appears that even with scale_fluid_usage = true, the heating towers continue consuming fluid after reaching 1000°, so it would still work as a voiding strategy in that way, though at a slower rate for fluids with a fuel value beyond 2.22MJ per unit. Fluids below that amount would still consume the full 6 fluid per second, or however much is provided, whichever is lower. Whether the devs choose to set scale_fluid_usage = true is their decision, as is whether or not they increase the limit on how much the heating tower can produce or decrease the rate at which it consumes. I'm merely presenting my observations and some data.