At Face Value
If what they're saying at HERE is the truth, they didn't decide to drop support for Windows 10 because they didn't like Microsoft, but for technical reasons that would have made continuing support uneconomical.
And it also means that since it's a workaround for a fundamental incompatibility that's breaking, that what Microsoft did on its end may have been a legitimate step to improve the security of their operating system.
I'm surprised that an application to display maps on a mobile device has to somehow break the rules software developers are expected to follow, and resort to hacker-type techniques in order to provide its basic functionality. But given the statement that it could work if rewritten from the ground up, likely that is not the issue, the problem could be that the app derives from legacy code written for the Windows desktop, i.e., Windows 7 or earlier.