Tow company wont release car because of expired tags?

My boyfriend’s car got towed from our complex for an expired tag. He called the company this morning and said they won’t release it to him (even if he were to pay their fees) since his tag is expired. Googling this says they don’t have the legal right to keep it, but there isn’t much information on it when an expired tag is factored in so I’m not sure.

Mind you, the tag has been renewed and paid for but the sticker never came and a replacement has not been requested yet. The tag is 3 months expired… Idk what to tell my bf there genuinely, but I needed to add this detail for the sake of getting the right answer.

Can they release the car or will it have to be held until he goes to the tag agency?