Don't forget:
1) they have per-emptively excluded themselves, and ALL state security agencies. There will be no checking up on politician's messages. There will be no checking up on police communications. No checking up on secret service messages (not even for the many public activities of such services). There will be no double-checking what the IRS tells it's agents. There will be no checking on school teachers.
In other words: clearly these politicians see the value in hiding what they themselves do, and in hiding anything that might result in liability. There is no need to explain this to them.
Rather, the question to ask them is what they are asking us: "Why aren't YOU breaking with the 'totally erroneous perception' that you, a public servant, can't be checked upon?"
2) This even applies to WHAT will phones be scanned for. The politicians see no need to have public discussion of what they'll be searching for. Since they are obviously carefully choosing what to hide and what to show, the question should be framed correctly:
"Why won't you tell us what you're scanning people's phones for?"
"Also, give me your phone, I've got some things I want to check it for ... What exactly? Why do you expect ME to tell YOU that?"
3) Why they are letting foreign companies do the phone scanning? I mean you're going to let the security services scan phones to help secure the state ... and you're getting a FOREIGN company to do this? Again the question should be framed correctly:
"Can you show me what grades you received in kindergarten? Did you ever get your head stuck in a chair for 9 days in a row?"