Being a factor of 2-3 times out in several places could mean something like +/- an order of magnitude here and given that this guy has his estimate two orders more than the previous suggests that this is an extremely imprecise bit of math going on. Being +/- two orders of magnitude out on the amount of watts the sun kicks out is not that big a deal, but here it makes the difference between the biggest animal being a cm high to about 100m.

If you could say with some certainty that the maximum for this planet is within that range tho then it does have a useful purpose if your looking for mammals on extra solar planets. If within two orders of magnitude of precision you could be certain that for a given planet it could only have 1mm sized animals of any shape then it kinda cuts down on what planets it might be worth pointing the life sensing spectrometers or cut down that absurdly woolly equation for aliens in the universe probability.

An odd paper and one I thought was BS to start with.