alt Hacker NewsThe market is small, but I wouldn't be surprised if there was a significant overlap between those who want a keyboard and the target audience of the Jolla phone.
Don't forget that SailfishOS is ultimately Linux (and not like Android) - it even comes with the zypper package manager that lets you install apps and update the OS using the terminal. Part of the fun of using SailfishOS is doing familiar Linux systems managements and general operations the terminal, which any Linux nerd would love. And Linux nerds make up a huge userbase of this OS.
I mean, look at the link OP pasted, they're straight up calling it a "Linux phone", it's clear who their audience is. And don't tell me majority of Linux users would NOT prefer to have a keyboard.
They're probably not interested in the Linux power user. They're interested in making their phone viable for everyone else, since that's a much bigger market, and for that customer base, a keyboard is very much going to be a negative and not a positive. The Linux part of their Linux phone also has the same problem, but they apparently have faith in that part.