What aitch said.
Also: mine loved tasting food (started at 6 months) but only started eating properly at around 8-9 months. Before that, if they were truly hungry, they asked for milk.
I believe in retrospect that I could easily have weaned them at 8 months. And they wouldn't have missed out on different tastes either - they were bf and were getting the taste of garam masala and all sorts from the day they were born.
It's important to be accurate when you're talking about evidence based guidelines.
WHO (and many other experts) have concluded that breastmilk is complete nutrition to at least 6 months, ie they don't need food before then. No more, no less. It's terribly important not to read your own personal theories into that statement.
To date there's no evidence at all for an upper limit of when you have to start food. Probably it's different for each child but it could be anything. Nobody knows.
Oh, and the window of opportunity thing is rubbish. In some places, many children aren't weaned until they're two YEARS old, and somehow they manage to eat and speak.
So as far as I can see, there isn't a shred of evidence that what this woman is doing is harmful. In fact, it's quite possible that she's the one who's right, and that all of the rest of us weaned too soon.
I hope not, obviously, and I think BLW is a very sound way of deciding on weaning age so I'm comfortable with what we did, but there's no way I'd jump in with both feet and call her an idiot because if new evidence comes out I might well be the one looking like an idiot.