JBossDeveloper

Any remote clients connected to the live server when it fails will fail-over to the colocated backup.  As long as those clients are connected they can consume messages directly from the colocated backup.  For other clients, they can consume the messages from the colocated backup indirectly as the messages from the colocated backup will flow to the other live servers in the cluster if redistribution is enabled.  That is why you can't set redistribution-delay to -1 in a colocated topology.

The documentation you cited already says this effectively at the end of section 38.1.1.1.2:

When the backup becomes it will be not be servicing any JEE components on this eap instance. Instead any existing messages will be redistributed around the cluster and new messages forwarded to and from the backup to service any remote clients it has (if it has any).

Moreover, Andy said essentially the same thing in the first reply on this thread:

your messages are sitting on the backup server, since you have redistribution turned of they will stay there until a stand alone client connects.