I agree with OP's interpretation.
From echoes rulebook, "...You meld that card immediately, and then you may take a free dogma action, selecting that card to activate."
"And then" establishes chronological order, but not a cause and effect relationship. So whether the "meld that card immediately" event got nuked, the "you may take a free dogma action, selecting that card to activate" still happens.
There's no rule that you can't activate dogmas of cards that aren't on your board, the game is structured such that you have permission to activate the top cards on your board, and maybe you can get permission some other ways too. This is apparent with the light wording on that-figure-that-lets-you-activate-others'-blue-cards. It's not as forceful as saying you activate that card as though it was your card, because it doesn't have to be, it more gently says to add that blue card to the list of cards you can activate whenever you like.