The obvious answer is no to me - if Beeminder helps something become habitual, why would you then take that support away? That’s like saying an umbrella has kept you dry, so you don’t need it anymore (as RBG said about the Voting Rights Act).
So I don’t think it’s a blindspot to intend to keep your goals as long as you want them. The crutch analogy suggests you need to heal from some sort of injury, and once it’s healed, then you can stop using it.
But I don’t believe that akrasia is something that can be healed from, the way a broken ankle can - I think it’s a human limitation that we use tools to overcome, and I haven’t seen much evidence that we can “heal” it with Beeminder. I see Beeminder as a tool to fight akrasia, and if you take away the tool, you lose its benefits.