Ofsted report was published on 10 March 2015, which is when the story hit the news, just like any "inadequate" Ofsted report of a school hit the news in the last months (the free school in Suffolk, one Islamic school, for example). Ofsted does inspect private schools by the way, not just early years, although they can opt to be inspected by the ISI, but Hill House didn't (probably for a good reason).
Of course there will be interest in this from non HH parents, this is the biggest prep school in London after all, and many on here are London parents looking at options. I don't see anything strange in the interest by others in this story. Many on here may not have children there but have friends with children there.
But I do agree the report looked very biased. I can understand the part about safety procedures, and there may be gaps in teacher training or marking, but "inadequate" is a really really bad rating for the quality of education. I am sure there is many a "good" rated Ofsted school with far worse teaching. There is probably quite a bit of tutoring going on (as in any London prep school), but even with a few hours of tutoring, you won't get children into King's College Wimbledon or Latymer Upper if the rest of the education is "inadequate". The children learn reading and maths in Reception just like in any other prep school, they do French, History, Geography etc, they are set by ability in higher years, so clearly there is differentiation by ability and the school must know where the children stand in order to set them.