Allard literally started the last game and they decided not to let him go again after Walker was the better pitcher that night. But it's really just a matter of order/semantics; if this game isn't winnable Allard is probably the next reliever.
It was definitely an unfortunate decision to send him down the first time, but he was mostly lucky. And pitched very poorly for much of his minor league season. I still have no problem with them having more faith in Walker's experience and past results (meaning last year). It's just baffling they haven't been able to really fix him at all. The kind of thing that does usually end up with a surgery or retirement at some point. Happened to Halladay and Lee (and has has been noted, Adam Eaton), could certainly happen to Taijuan Walker.