I don't think they are overclaiming. From the abstract:
> we present Constantine, a compiler-based system to automatically harden programs against microarchitectural side channels [...]
> secret dependent control and data flows are completely linearized (i.e., all involved code/data accesses are always executed).
Their goal is to hide microarchitectural events from a passive or active observer. As a side note, the VUSec research group helped discover microarchitectural side channels such as Rogue In-Flight Data Load [0] and I'm sure they know the difference between earlier work on timing and microarchitectural side channels.