Maybe they could maybe they couldn't, doesn't mean criminals couldn't.
MIE is opaque - Apple has not disclosed its design - it also means it can contain intentional backdoors and other security holes.
In other words this is just meaningless PR and doesn't change the fact that Apple's security is poor.
Apple only alerts people who are potentially in life threatening situations because of who they are or what they do:
Apple today detailed two initiatives to help protect users who may be personally targeted by some of the most sophisticated digital threats, such as those from private companies developing state-sponsored mercenary spyware. Lockdown Mode — the first major capability of its kind, coming this fall with iOS 16, iPadOS 16, and macOS Ventura — is an extreme, optional protection for the very small number of users who face grave, targeted threats to their digital security.
“Apple expands industry-leading commitment to protect users from highly targeted mercenary spyware” — https://www.apple.com/newsroom/2022/07/apple-expands-commitm...