I assume the problem is that these are secure actions, which have to be handled with care. Most LDB displays don't support secure frames.
Since Ora takes care about IsCombatLocked in most situations I guess this should not be a problem since I use "standard methods" to do those things.
But since you can do the things I do with the Ora menu also (but a bit more complicated) I guess this will also work.
AFAIK CTRA / Ora do queue the actions.
So if I'm (let's say) somewhere out the instance and the rest of the raid is fightin their the following (as far as I remember happens):
I (out of fight) set an MT.
--this results in an addon message sent to all members
I see the new (changed) MT list imideatly
The other raid members see the list (change) after leaving combat.
BUT - with PTs I'm not sure - I'll take a deeper look at this.
By the way - this "secure frames thing" is not very new - and Ora had this abillity until patch 3.x
I'm confused. Can someone help me understand why a seperate addon is needed to have ora2 regain this pre 3.02 ability? (can't the ora2 LDB code be modified so it now "just works", using the method you describe?)