Company not matching 401k after getting laid off

Not sure if this is the right place to post this. A family member of mine just got laid off. They worked as a personal banker and apparently, their company does 401k matching by providing a lump-sum at the end of the year. This is the first time I've heard that - I assumed that every company was matching monthly. The lump sum is usually given at the end of December but because they got laid off, the company is saying that they won't be doing any matching at all for the year even though they worked at the company for 10 out of 12 months.

Is this legal??? If the company was doing the monthly system, they would have had the money but this feels like the shittiest loophole I've ever heard of