With the passage of the Economic Growth, Regulatory Relief, and Consumer Protection Act which was signed into law on May 24, 2018, security freezes do not apply to the making of a credit report for use in connection with "employment, tenant, or background screening purposes" (see Sec. 301(a)(4)(I) of the Act [page 34 of the PDF below]).
https://www.congress.gov/115/plaws/publ174/PLAW-115publ174.p...
To be fair, I'm not sure if the same rules apply to whatever type of "freeze" the work number offers. I'm not even entirely sure it's regulated at all.