That's exactly what it is. I worked at IBM many moons ago, and at one point was asked to create a list of job requirements that would ensure I was provably the only person in the world who met the constraints. Big companies are weird, man.

It's also how procurement works in the public sector. Either of their own, or with a help of an external consultant, public sector workers will create a set of requirements that are tailored to fit a particular desired supplier, with a bunch of extra bullshit requirements thrown in so that technically allows other competitors, and doesn't look obviously illegal.

Once worked with a network guy who always specced out EIGRP as a requirement to ensure he always got Cisco routers.

Suddenly that contracting company asking me to fudge the wording on my work experience is starting to make sense...

How would this comply with the law if an external candidate would have no chance to pass anyway (due to work experience required with an internal tool not available to the public)?

Wouldn't posting a job that an external candidate has no chance of obtaining still violate the intent of that law?

There can be external candidates with that qualification. In general the standard is “Bona Fide occupational qualification” which means that you have a legitimate reason for the requirement. For a college hire this would likely not suffice ... you can teach a college hire what they need to know. For the engineering director running the project it very well might be.

Incidentally, a bunch of people outside Microsoft had access to these tools (e.g. academics).

The job posting lists it as something preferred but not a hard requirement.

Don’t forget former employees.

I wonder if you can still apply if you're managed to sus out the requisite experience through reverse engineering…

Depends, some places only want to count experience if it can be linked to hours you billed.