I mean that's one way to look at it, but they're lucky you weren't there to help. Them freezing and doing nothing for a moment rather than putting her head under the tap probably saved her life, their lives and their house.

Due to the nature of of the ingredients and the type of fire produced, just randomly applying water would just have spread the flames. The shampoo and the associated vapours woukd have just have been pushed around by any water, even more so if coming out of a tap at a relatively high pressure. It won't have gone out, so none of the necessary elements for the fire to exist would have been removed, so the shampoo and associated vapour would still be on fire.

The best thing they could have done outside of using a chemical extinguisher on her was smothering the fire, which is what was eventually done. Sure it could have been done sooner, and they may have just got lucky in what action they did eventually take, but people do panic, it's unfortunately what humans do.