That is still a lay off. If the company is acquired you don't get to pick and choose what contracts it had are valid, you have to argue your new contract is similar employment terms or you have laid someone off.

If everyone were laid off before the company was acquired, why wouldn’t the new owner get to choose who to employ?

Do you perhaps know how this works legally? I'm curious. Did their contracts under Epic say something in the lines of, "on the event of ownership change your contracts are null and void" just like that?

My estimation is that Epic sold all of the IP (name, other trademarks, code, infrastructure, etc) along with the right to be the successor to the extensive license agreements and contracts that they held. Included in this is HR records, which allows the new owner to make offers to the folks that Epic is no longer employing after the deal finishe(d/s).

M&A transactions can get pretty complicated for exactly these reasons; frequently, they disassemble the entire set of assets for sale and divvy them up across one or more buyers, who will pick and choose what they want and then reconstitute whatever they have purchased to their desired degree.

"Hey, we sold your entire department's work to this subsidiary, but we're keeping you as part of the parent company. Oh look, there's no work for you to do! You're all laid off. I hear this new subsidiary is hiring."