On its 10th anniversary, Signal’s president wants to remind you that the world’s most secure communications platform is a nonprofit. It’s free. It doesn’t track you or serve you ads. It pays its engineers very well. And it’s a go-to app for hundreds of millions of people.
If he was using their VPN, they wouldn’t have been able to turn that over according to their own site: https://protonvpn.com/features/no-logs-policy#:~:text=No-logs VPN,lengths%2C or location.