Actor model does not need CSP. Erlang uses single message passing queue per thread (process in Erlang terminology) with unbounded buffer so the sender never blocks.
As the article pointed out lack of support for unbounded channels complicates reasoning about absence of deadlocks. For example, they are not possible at all with Erlang model.
Of cause unbounded message queues have own drawbacks, but then Erlang supports safe killing of threads from other threads so with Erlang a supervisor thread can send health pings periodically and kill the unresponsive thread.
As the article pointed out lack of support for unbounded channels complicates reasoning about absence of deadlocks. For example, they are not possible at all with Erlang model.
Of cause unbounded message queues have own drawbacks, but then Erlang supports safe killing of threads from other threads so with Erlang a supervisor thread can send health pings periodically and kill the unresponsive thread.