My take: low-yield could in fact be a sign of a well-engineered trigger, since
pouring on more hydrogen just gets you to the megaton range. Of course, the
only reason for that hunch is that the Administration would have leaked that
failure, if it was one, much earlier in the news cycle.
But it doesn't help that Indian politicians are putting out such transparent
lies as "oh, the seismic waves cancelled each other out".