If you go to an account on mastodon.social, like mastodon.social/@kevinmarks you can see that it now verifies rel=me links:
However not all mastodon instances have updated to 2.6.1 yet, eg xoxo.zone/@kevinmarks
Help is at hand though - with the verify-me chrome plugin it will check when you click the green tick:
And if you go try this on the mastodon.social version, you can check their checkmarks should be checked:
Which is helps see if aral is being sneaky.