As soon as Narayana will be built against wildfly master branch the variable JBOSS_BIN can be restored here: https://github.com/jbosstm/quickstart/blob/master/XTS/ssl/xts-over-ssh.sh#L31
It will be comment until wildfly 27.0.0.Apha1 is used in order to force the clone and build of master wildfly (see here: https://github.com/jbosstm/quickstart/blob/master/XTS/ssl/xts-over-ssh.sh#L154-L166).
It will be comment for issue JBTM-3670, see PR https://github.com/jbosstm/quickstart/pull/403