  A closed subgroup $H$ of a locally compact group $G$ is confined if the
closure of the conjugacy class of $H$ in the Chabauty space of $G$ does not
contain the trivial subgroup. We establish a dynamical criterion on the action
of a totally disconnected locally compact group $G$ on a compact space $X$
ensuring that no relatively amenable subgroup of $G$ can be confined. This
property is equivalent to the fact that the action of $G$ on its Furstenberg
boundary is free. Our criterion applies to the Neretin groups. We deduce that
each Neretin group has two inequivalent irreducible unitary representations
that are weakly equivalent. This implies that the Neretin groups are not of
type I, thereby answering a question of Y.~Neretin.
