This does seem to be an implementation bug. I'll refer it to the Product team for investigation.
As for a workaround, are there no more reliable sources for doing a version check? Typically version checks are done by file. Sometimes a product embeds the version in a registry value.
Let's talk about the need to use StartsWith/BeginsWith?
Typically an Applicability Rule is implemented as a LESS THAN comparison against a specific four-part version number. Understanding your specific atypical use-case will help identify an alternative approach.