I don't see any issue with this title. A "source code dump" is usually an act of vandalism, as opposed to a "source code release", or "released as open source". Additionally, there was source code available. It appeared that Vine was/is written in an interpreted language, so by downloading the wwwroot Docker image, the author was capable of reading the entirety of the Vine application code without any weird decompilation or deobfuscation steps.

No, you can't personally go replicate the steps the author performed to retrieve the Vine source code on your own today, but that's the nature of responsible disclosure. Vine was responsive to the vulnerability report and closed that leak, which enabled the author to create this writeup of what happened.