Here's my guess.
It's a bit hard to tell from the photos, but the OHs don't look like they're pointing directly at the cymbals, but further out to the side. So the cymbals are off axis as well, though not to the extent that the snare is. But since cardioid typically mics don't have a uniform pattern at all frequencies, this may actually have the effect of better balancing the kit than if the OHs were pointing towards the centre. The high frequencies response would be narrower, almost hypercardioid-like, compared to the wider patter of the mids. So the cymbals may actually end up being attenuated much more than you might expect them to be in this configuration, whereas the snare, being a lower frequency output and being picked up equally in both mics, might not be louder than you might expect.
Admittedly I'm making a few assumptions here but it seems like a possible rationale to me.