I don't understand why there is even a need for this?
I'd venture a guess that this is happening the way it's happening (rotation of specific operations) because nobody is really running older operations.
Yes a guild run might happen to get a title or a speeder achievement or something but that's it. If you're 2 years late to the party and you just hit 50 you're basically SOL trying to get an EV, KP or EC group to see the story. It just never pops and I can remember like 2 times in the last half a year I saw someone trying to make a story EV group in general chat.
This way when EV is up for 30 comm rotation it will actually pop and a couple of 50s can get schlepped through the operation each run. And so they don't get booted the second someone sees sub 25k HP in operations frame they get bolstered.