It seems like they moved the article to tkrunning.com, which is a Medium custom domain created before Medium custom domains were disallowed. From there, tkrunning.com is behind CloudFlare, so I would guess they used CloudFlare's Page Rules, which lets you (among other things) setup 301 redirects at the CloudFlare reverse-proxy level.
I don't believe I'm violating their ToS, but you never know how they would interpret it. That's why I'm not sharing it publicly. But feel free to email me on mediumtrick at nomad dot email.
I don't think Medium is able to plug the hole that easily, but they might tell me to stop doing it or plug the hole just for me. I don't believe I'm violating their ToS, but you never know how they would interpret it.
No, it's not that, and I feel silly for thinking it could be that, because it would require iframe busting on a sandboxed iframe.
I think it has to do with being able to use Medium on a custom domain. I think perhaps Medium validated that the DNS pointed to Medium once and stopped checking.
Is see he uses an intermediary redirect (not sure why):
https://medium.com/nomad-gate/estonian-e-residency-ultimate-...
->
https://tkrunning.com/estonian-e-residency-ultimate-guide-ba...
->
https://nomadgate.com/estonian-e-residency-guide/
I'm guessing here but maybe medium allows redirect to tkrunning.com for some reason, and it in turn allows redirects anywhere.