It's a good suggestion, although I suspect at this point Stu is more concerned about not being able to buy an outbound non-stop as part of a return ticket, than whether he gets status miles, or has a chance at an upgrade.
What's going to happen if they end up with only one mainline flight each way, and one of them isn't useable? No one's going to pay the one-way fare on mainline, and one-way on tango coming back, so then what? I can see the mainline flights being full of tourists, who have flexibility in when they fly, while the tango flights fill up with businesspeople who (like Stu) can't work with the mainline one way.
What AC may have to do, is offer a cheap one-way fare on mainline if you also buy a one-way on tango.
andrew