That is kind of surprising given he is on the comittee investigating pegasus. I'd assume someone on the comittee would be paying much more attention to this than a normal person.
I wonder what triggered him to suspect he was hacked then. Since presumably something triggered him to have his phone forensically investigated.
If he knew he was compromised, and was okay with it for one reason or another (like money or other coercion), this is what his cleanup would look like.
Not saying this is likely. Just another possibility.
Or that Apple could either run searches on the names of affected users against publicly known members of government or have close relationship with governments to flag exactly this.