I wonder if the police would have let her through had there been another sort on incident on the motorway causing it to be closed?
A crash or a toxic spill are not the same, usually you aren't allowed to continue if it's unsafe for you or the people at the scene. As with most, I'm broadly in favour of the protestors aims, but it doesn't help them resonate with the public if their leader/spokesperson is saying he's happy to let people die in ambulances (for example).
I appreciate the protests are designed to get attention from the wider public and pressure the government but when you have a government who doesn't give a shit about the populace in general, I don't know that the aims achieve the desired result. Chances are, an increasing part of the population think IB/XR are loonies bordering on terrorists because of the press rather than increasing numbers of the population thinking they're doing good.