Why would you be ineligible for rehire after a downsizing?
Most likely to avoid someone returning on false pretenses to retaliate against being downsized in the firstplace.
"Lowest performers" doesn't imply bad performers (e.g. a strong team of A & B players).
Also downsizing can happen in different ways. For instance: "we're closing this whole site and laying off everyone who works there," or "this project failed [due to bad leadership], so we're laying off the whole team."