BA can never win whatever they do. It's always irksome when someone else has what we want. But.
For what it's worth BA are a company like any other who happen to be in the Airline business. If they are ever going to convince management of other companies to use the F product for their senior people's business travel then they should be using it for their own senior people's business travel. And for those people in BA entitled to F travel when on business then they just like customers of BA who have F travel as a part of their package should be entitled to expect there to be a seat for them if one is available when they make the booking. They shouldn't be bumpoed because another passenger wants an upgrade. That wouldn't be fair to the BA executive who is also entitled to a degree of reasonableness and fairness. The upgrade wasn't available for the OP because the seat had been taken by an executive of another company - in this case BA - who was entitled to be there.
It is an entirely different case when it's non-business travel as has been stated by many who know.
^
If BA's staff on duty travel policy allows said member of staff to sit in F, then they should be a confirmed passenger in F. Policies exist to give certainty - if you or I don't expect to suddenly have our J class seat changed on a whim by our employers, why should a member of BA staff travelling on company business, just because they happen to work in the airline industry?