I could be wrong, but I think you are registering to receive the PoCo::IRC's events from within the PoCo::Server::TCP session. It boils down to whether the client_input state is attached to the PoCo::Server::TCP session or to your session. The PoCo::IRC component could be sending events to the wrong one.

Update: I believe my post is correct. I have modified massacred your code to see which session is being called:

use POE qw(Component::Server::TCP Component::IRC);

POE::Component::Server::TCP->new(
  Port     => '9999',
  Address  => '0.0.0.0',
  ClientInput => \&client_input,
);

POE::Session->create(
  package_states => [ main => [qw(_start)], ],
);

$poe_kernel->run();


sub _start {
  print "My session has id: ", $_[SESSION]->ID(), "\n";
}

sub client_input {
  print "Starting bot in session: ", $_[SESSION]->ID(), "\n";
}
[download]

And it outputs the following:

My session has id: 3
Starting bot in session: 4

So it looks like client_input is being called on a different session than the one you need to register with POE::Component::IRC. I would probably solve this by creating a new state in your session that handles the PoCo::IRC instantiation and registration stuff. Something like this:

use POE qw(Component::Server::TCP Component::IRC);

POE::Component::Server::TCP->new(
  Port     => '9999',
  Address  => '0.0.0.0',
  ClientInput => \&client_input,
);

POE::Session->create(
  package_states => [ main => [qw(_start create_bot)], ],
);

$poe_kernel->run();


sub create_bot {
  print "Starting bot in session: ", $_[SESSION]->ID(), "\n";
}

sub _start {
  print "My session has id: ", $_[SESSION]->ID(), "\n";
  $_[KERNEL]->alias_set("mine");
}

sub client_input {
  $_[KERNEL]->post(mine => 'create_bot');
}
[download]