The resistance was caught in the process of evacuating their not-so-secret base, outnumbered and staring down the huge barrels of a fleet-killing weapon. Yes, Leia ordered an evacuation, but we have no way of knowing if it would have been successful.
They certainly imply later that the firepower would have been adequate of dealing with the Resistance, when they showed the Dreadnought targeting the Raddus. If the Fulminatrix had been part of the First Order fleet after they tracked them through hyperspace, the Resistance, i feel, would have been utterly destroyed.
So yep, i consider them heroes of the Resistance.
That said however, the less said about TLJ, the better 😀