It looks to me that the certificate is installed right the first time, but then VUM keeps retrieving the original certificate, rather than updating it when it changes.
So a re-install will fix the problem for however long your certificate is valid, but I don't think it is a permanent fix.
So far, I've just kept reapplying my patch whenever I update the VCSA if I have to - it seems to revert it on some updates but not others. I haven't had a problem doing that, so either the patch is still needed or it is at least doing no harm to the newer versions
For every version of VCSA through to 126.96.36.199100 the original vumUtils.py was binary the same as the version I created my patch against, so either VMware still haven't looked into this, or they have fixed it in a different way.