A format change might qualify as a reboot.No. It was a spin-off continuation.
I suppose it could in general. But in this case, the TAS writers guide was just the TOS writers guide with a little extra material, key writers were TOS alumni, in some cases writing direct sequels to TOS episodes and in others revisiting TOS planets as they had been conceived in TOS or continuing the adventures of guest characters from TOS, TOS guest stars returned playing the same guest characters, not to mention the main cast was almost all the same. Even the life-support belts, one of the more visible differences with TOS, were a concept originally developed for TOS but rejected because they couldn't pull it off. TAS just doesn't qualify as a "reboot" in the sense of jettisoning continuity and going back to basics. You might call it an upgrade in a sense (and a downgrade in others), but the premise and continuity of TOS remained intact when it was inherited into TAS.
As a follow-up to this, I would agree that the term "soft reboot" fits TAS, as it also fits both TNG and ENT.