it's listed under the 'debugging' tag, which means the code is bad and needs to be fixed.

Given that the task is very specific I'd say it is, as it is performant and the code is readable.

If you had to, for example, generate neighbors up to a variable distance n received as a parameter of the function, that would be a different story.

Well, the kata description already says so: 'Something is wrong with our Warrior class.' — And, indeed, it is.
The initial Ruby code is pretty bad, too. (And not only because it doesn't work [correctly or not].)

Fixed both issues

I'm pretty sure it's against good practices in all languages, but hey.. you should be able to deal with this kind of code in a software development team since not everyone are experienced