Worth getting a lawyer?

We are Canadians living in Illinois. My husband has worked for the same company since 2018. In 2023 they asked him to transfer to the USA. Same company but USA entity.

They recently announced they are shutting down the site they moved us to. My husband found a new job with a new company and will be starting soon. The problem is the original company said their pension contributions made while we were in the USA will not have vested by the time he quits. They don’t recognize his years in Canada as time with the company. (However they do recognize them for severance and vacation time) So he will be a couple months short when he quits.

My question is would getting legal advice be worth it here and if so, what kind of lawyer would we need?