From what I’ve seen, she was already getting off of the bus therefore was under no obligation to show the ticket inspector her Oyster card, which is why she was walking away.
Some of these inspectors are shockingly rude, similar happened to me a few weeks ago. I’d got on the bus tapped with my phone but it didn’t connect properly to the reader, the inspectors got on so as usual tapped my phone on their reader which showed I hadn’t paid my fare.
I apologised and tapped it again as I was sitting right next to the driver, this time it paid the fare so I went to sit back down, the inspector told me he was going to give me a fine for my unpaid fare asking for my name which I refused to give as I had paid, he started shouting in my face telling me he was calling the police, being very intimidating, even the driver was shocked and apologised as I got off the bus after a shouting match.
TFL are an absolute shambles, they don’t even take the fares straight away and take them randomly as and when they feel like it.