VxWorks showing up in another NASA deep-space instrument makes me wonder...is it NASA’s lucky pair of socks, or is Linux still not “good enough” for this kind o

VxWorks showing up in another NASA deep-space instrument makes me wonder...is it NASA’s lucky pair of socks, or is Linux still not “good enough” for this kind of mission? Even with what SpaceX is doing with Triple Voting linux based COTS. Whays the rationale?