you could test your own test by making sure that it produced the same results with Test::More

How so? Because if Test::More is present, the test suite is run with Test::More, and not with myMTBLikeTestMore, so you don't compare the output of myMTBLikeTestMore because it isn't run, and if Test::More isn't present, you can't compare the results of myMTBLikeTestMore with Test::More either.

Seriously though, it seems like if Test::More isn't going to be in the core (is it?)

Test::More has been part of the core distribution since 5.8.0.

then people ought to be able to distribute it with their modules

Test::More has an Open Source license, so you're free to redistribute (and modify) its code.

Abigail