If you were stupid/defiant/idiotic like "I deliberately buy a route Not London ticket, avoid the guard where possible, double-gate through barriers and they can't stop me because all they can do is excess" then I think the answer is yes, you can get an MG11 and you'd deserve it!
On the other hand I do not see how a reasonable person can reasonably be issued with an MG11 for being genuinely off-route*, unless the RPI is an absolute..... which, unfortunately, some of them are.
So I am going to say "maybe" on this one, which of course isn't of much help to the OP. I need to know what happened in the case that the OP refers to before I can give an opinion on this particular case (whether it happened to the OP, or a friend, or anyone else the OP knows or has heard from).
* What I mean by genuinely off-route, is that I am not counting it when people go over-distance or deviate from the route. e.g. if you invented your own silly route that wasn't in the Routeing Guide, such as London to Stevenage via Euston, Inverness and Aberdeen, that is NOT off-route, that is massively deviating/over-distance and The Manual would give rather different instructions compared to a change of route.