Excuse me if I'm missing something, but isn't an entry gate a bit irrelevant for a high performance jet anyway?
That's not the issue here. The issue is whether the display authorisation limits were breached. If the limits are very clearly defined in writing (including the distinction between a normal vertical manoeuvre and one commenced from a low fly past), and the pilot is proven to have knowingly breached them, then I suspect there will be a prosecution for involuntary manslaughter. If there is no clear definition of minimum altitudes and speeds to enter the manoeuvre in the display authorisation then I doubt that the CPS would prosecute, because there is no precedent to do so (though no doubt the CAA would be advised to tighten up the wording of the limitations for future display authorisations, if an inappropriate entry configuration was the cause of the incident). Of course, if it is shown to be a technical issue, or pilot error during the manoeuvre, then there would be no prosecution.