John@home
yeah, I actually agree with Mojo too (just don't tell him that)
I would quote your post but to be honest I don't seem to have much luck in that direction (must not be permitted

)
What I will say in response to your post is I think the problem lies squarely in the training procedures for revenue staff and specifically with the 'glossing over' of the Routeing Guide. In fact they pay it little or no heed at all.
Scotrail conductors are now no longer even issued with a Ticket Examiners handbook, and those that were are now no longer required to carry one as part of their issued kit. They have no source of reference and must rely on what they remember of their training. As new developments occur . . . . well nothing really . . . . there are no updates for a handbook which is no longer supplied.
For all the fact that passengers are left to their own devices to divine the mysteries of ticket types and validities, routeings and easements, the revenue staff have little more information at their disposal.
But effectively, all staff at all times were instructed that tickets on the Fife circle were not valid if it required passing through a point for which a higher fare was due. Scotrail did not want passengers purchasing a single from Edinburgh to Rosyth for £4.20 and travelling to Glenrothes (a fare of £6.80) by way of Kirkcaldy. Thus has it always been so, even prior to the negative easements to which you refer.
As to the conductors objection vis-a-vis the break of journey as opposed to the use of a through train - this again I would put down to no information coming from Scotrail to it's frontline staff leaving the conductor to invent something which sounded plausible because he knew he wasn't supposed to allow it without really knowing why.
Of course he may have allowed it if the passenger had intended to go to Dalgety Bay in the first place and simply ended up on the outer versus the inner circle service in error. Who knows?