I read that, too. As a retired Horticulturalist, I can tell you that’s BS. Hawaii’s grasses/foliage is just as combustible when dry.
Here in West Texas our biggest concern is high winds and hi-lines. They can snap the lines or they come in contact with each other. Both send a shower of sparks below. Did a street view on that area and most of the buildings seem to be wood and asphalt roofing. Plenty of fuel and high winds can be devastating. Seen one fire move so fast the Texas Forest Service had to set up their line 4 miles in front just to get ahead of it.
Might not different varieties coming in provide MORE fuel? Case in point: On one part of our property that I normally mow only every month or so (its not the lawn immediately adjacent to the house!) some sort of new grass has “invaded”. (I’ve not yet researched what it is.)
So, there’s this one several square foot patch of grass that literally grows 2-3 ft. tall, fairly densely, with blades ~ 3/8” wide and with a fairly heavy center “keel” (prolly the wrong terminology?) to each blade, in the time it takes the rest of the grass in our yard to grow maybe 6”. (I’m not considering the seed head heights.) I don’t know what the final fuel per square foot (acre, hectare, etc.) ratio of this stuff over the grasses we’ve had here for ~35 years prior might be, IF I let both grow until fall and then dry out, but it has to be substantial.
Even taller new plants coming in also seem like a possibility. Heck, here in the lowly mid-south USA we have weeds that grow over 10 ft. tall. Esp. if we get a wet July (like this year).
Height of the “fuel” can matter too, in and of itself. (Vertical dynamics of the flames.)
Some years back, I saw a small cornfield that didn’t get harvested for some reason, go up in flames. THAT was rather impressive, too. :-(
Granted I’m just speculating. Do you have Horticulturist friends in Hawaii who could weigh in?