I have tried to explain that there is in general no problem by including an unmodified released official binary, of course you should take you own legal advise.
https://forum.sumatrapdfreader.org/t/license-commercial-use-distribution-with-3rd-party-software/536/34?u=githubrulesok
Not the ONE developer but historically Zoom is unlikely to be added to the light/fast thumbnail/previewer (which has its own issues), it is only made available in the slower exe which can be called as a restricted plugin.