It is not absurd.
A normal e-mail client doesn't suffer from this issue. Only if the user is hosting their e-mail traffic inside the US. You may think that's true for everyone, but that is your own bubble or tunnel vision. Say, you are working at the EP (European Parlement). You use Mozilla Thunderbird for your e-mail. Some of the e-mail you receive is internal from your party. The SMTP and IMAP server is hosted in your European country. Then, one day you switch from Mozilla Thunderbird to Nylas N1. Suddenly, your e-mail is not hosted in the EU anymore, and the US government can use a NSL to read your private data. You may not give a rat about this (and if you're from US I can fully understand), that's your discretion. Others do, and their viewpoint is not 'absurd'.
> Which supported service is not already running in the USA and subject to NSLs?
Any SMTP and IMAP server not hosted in the USA. You know, you don't have to use Gmail.
(Nylas Mail doesn't suffer from this problem. Only a few features still require Nylas servers.)
