If you can’t reach the command line in rescue mode you may use the emergency shell by adding rd.break (as @Colin said to me ) as boot parameter at the end of kernel command. In the shell the root partition is mounted automatically into /sysroot directory so the file to change in this case is is /sysroot/etc/nsswitch.conf.
And I still have had no problems at all with the former and the current update of glibc in one of my two computers…Would like to know why this particular laptop has shown no problem to boot. This makes me think that the root of the problem is not properly identified…