In summary, I can wholeheartedly sympathize with the IC2 team not wanting to add yet another edge-case to handle for some other mod's object. Who knows how many other fuel-like substances the RC team might decide to add in future patches.
The fact that this has been done in the past does not necessarily imply that it's the right thing to do in the future - it may have been the wrong thing to do in the past.
Supposing that we were to agree that it's the RailCraft team's responsibility to set a burn-value in anything that might be conceivably used as an IC2 fuel. Is there somebody we can approach who might be willing to consider this suggestion?
I'm still perplexed about the inconsistency issue: In the current DW20 mod-pack in single-player creative mode you CAN use creosote as a fuel in the semiliquid generator. For some reason it does not work in my multiplayer Survival-mode game. Can anybody think of a good reason why these objects might behave differently?