I'm not so sure. I watched the exchange live and it seems perfectly reasonable that a person might have some apps that the FBI did not have the encryption to. New apps come by every day.
Further, the bigger question is whether we WANT the gov to have access to everything, can they be trusted? History says no. History says that given the power, the government will abuse it.
A few years ago, there was an issue with Apple computers and the government begging Apple for the backdoor. Apple said Nyet.
Of course, this raises the question of an assassin having encrypted accounts with a foreign enemy, but freedom and privacy come with risks. Total security comes at the expense of loss of liberty.
All of this being a MOOT point had the SS simply
- flown a drone around the area,
- checked out the guy with the rangefinder and either confiscated it or kicked him out,
- had better comm links between State Police and the Secret Service there, and
- put a man on the most obvious roof with direct access to Trump, kept a watch of that roof, and had pulled Trump from the stage so long as there was a person of suspicion in the area.
If I were a foreign enemy, I would be laughing at our DEI secret service and looking to make plans to really exploit it.