May I suggest that the mod instead siphons volatiles from nebulae and then a separate command to process volatiles to fuel, which would then be more efficient and effective with synchrotrons?
After all, canonically speaking, the raw material mined from gas giants is the Volatiles item, which has to be processed at a refinery. It may not be possible to directly use siphoned material from nebulae as fuel.
Additionally, being able to process from volatiles can synergize with Nexerelin, as that mod allows the player to mine gas giants for that resource, and this could also be an extension of that.
Lastly, it may make sense for siphoning to cause a further reduction in burn level, or require sneaking (burn level 2) to avoid accident as a balance to obtaining resources.
Heavy machinery could make more sense for consumption, as siphoning fuel has no explanation for consuming supplies that heavy machinery cannot replace. Accidents for burning full-speed through a nebula while siphoning can otherwise cause CR reductions and damage, which should serve as a drawback to the player and bring this in line with Nexerelin's mining feature.
Also, it may be prudent to disable fuel siphoning activation during emergency burns.