When they're asking for some ability to perform searches and collect evidence, that's not necessarily counter to the US constitution. Quite the opposite in fact.
> Amendment IV
>
> The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
You seem to be arguing against a strawman created by a limitation of our current technology. We don't have a way to give them limited access. Right now, we can give them everything, or we can give them nothing. But they're not asking for everything. So we should find a way to allow truly (technologically) limited access, and to make sure that those limits are tight.
I'm specifically arguing against the generalizations the parent was making in particular. "Striving to reduce rights" of US citizens is generally anti-constitutional as a concept, especially for non-lawmaking organizations.
The 4th amendment doesn't really affect any of the original crypto argument, because the search cannot be performed. Cryptography prevents the "this is the way that's acceptable" act from even starting. Note that the amendment simply says that a warrant is allowable in a bounded implementation; it doesn't demand that warrants must be executable.
For instance, if a warrant is issued to search a non-existent building it's just as moot. It doesn't require the building to be created if it's not there.
https://www.law.cornell.edu/constitution/fourth_amendment
> Amendment IV > > The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
You seem to be arguing against a strawman created by a limitation of our current technology. We don't have a way to give them limited access. Right now, we can give them everything, or we can give them nothing. But they're not asking for everything. So we should find a way to allow truly (technologically) limited access, and to make sure that those limits are tight.