You're right that it's not a vulnerability of Ethereum. It's representative of a weakness of Ethereum and it's language which makes mistakes like this bug a lot more prevalent.

It's sort of how like a "use after free" bug in a program written in a non-GC'd language isn't a vulnerability of the language itself.

Languages encourage or discourage (or even eliminate) lasses of bugs based on their design. Etherum's is particularly bad in this regard.

As such, ETH is probably a "buy" right now.

Which is what the title, and the actual article say.