Shouldn't the Hofmann product be preferred in this elimination?
Yup, $\ce{t-BuO-}$ is a bulky base.

But is it bulky enough that it can't even abstract a hydrogen from the ring? Nope.

Take a look at this picture of a $\ce{t-BuO-}$ molecules approaching the hydrogen of 1-bromo-1-methyl-cyclopentane.



Does that $\ce{t-BuO-}$ look like it's struggling to pull that hydrogen out? Definitely not. It's doing what it does with ease.