At that price they should sell dozens upon dozens...
Tens of thousands I should hope
FWIW, the type of driver used to reach 300 lumens can have a significant effect on the efficiency of a low setting, thus the runtime difference. There is a very real lack of transparency in the flashlight industry, compared to the smartphone industry for example, so we don't really know much about the electronic components (i.e. drivers and IC's). This makes it difficult to ascertain what components are used and how they differ product to product and compare across companies.
In theory, the Cree XP-G2 (S4 bin) needs about 1.9W to reach 300 LED lumens (not OTF lumens). Assuming the use of a Eneloop Pro AAA 900mAh 4th gen, nominal voltage is fixed at 1.2V. This means that ~1.5A of current is demanded of the battery, which is 1.7C (rough interpolation of the latest AAA Eneloop Pro gives 895mAh at 1.5A). I say all this to say that a ~2W power requirement to run a light at 300 lumens means that max output can only be sustained for <36 minutes under ideal conditions even with 100% efficiency.
Ultimately, it all comes down to math. If the numbers don't add up, then it's not possible. Give Surefire's engineers some slack, at least until the product is released, they do this for a living.