Are there any technical reasons to request support for Perl 5.10 or older?

Bumping the minimum Perl version is a reasonable thing to do regularly and should be considered whenever a new Perl version is released. The new minimum version is 5.12, which was released more than 12 years ago. So, there is no contradiction in the rationale.

An obvious technical reason for bumping the minimum version is to limit the number of different versions for testing new releases. Also, CPAN authors might want to use features which have been added to the Perl core at some point in time.

So, to answer the question raised in your subject: This can be construed to be a concerted effort to break CPAN for older Perl versions. Older than 12 years, to be precise. The process is called software maintenance. However, it has nothing to do with driving support for V7, whatever that might turn out to be.