People always use that link as reference to say that Internet Archive ignores robots.txt but it only actually says they are ignoring it for government sites. It suggests that they might do it for other sites in the future (of 2017), but does not actually say that that they have done it.
That first link is confusing; it seems to say they ended up removing the pages not because of a legal threat but because of robots.txt “automated”.
If archive.org can be manipulated to remove content either via legal threats or simple robots.txt it loses a significant portion of its societal value.
The robots.txt file should be used to restrict (and, in some cases, slow down) crawling at the time it is being crawled, not for SEO or for restricting access to mirrors or for any other purpose. It should never apply retroactively. (Unfortunately it is sometimes used badly despite this.)
It's not about robots.txt but yes, the owners of 538 can just send a cease and desist letter to get them all immediately removed. Many sites that don't want to preserve history have done this already.