I was never a military lawyer so I don't know. In the civilian world it would not because it would be considered an interim ruling. A appeal of this issue would have to be part of an appeal of a final verdict.
Again in the civilian world, Lakin could go for a special writ with an appellate court to consider this issue now, but those are rarely granted. I don't know if military courts do those kinds of things.
They (interlocutory appeals) do exist in the military court system, but not with these sets of facts and circumstances. I won't bore you with the particulars, but his chances of prevailing with an extraordinary writ are virtually zero. For a variety of reasons, the appellate court will have to deny the interlocutory appeal. But, it is a point that Lakin's team can raise when he files his first appeal to CMA.
Having said that, his chances of prevailing on appeal to CMA and then to CAAF are close to zero, at least with respect to this particular judicial ruling. The MJ really had no choice. The existing case law, as she cited, binds her thoroughly, as it will bind the appellate courts.