martap,
the best way to achieve this without modifying any code, is to add an action script 'delete-auto-pseudonyms' that deletes the auto pseudonyms and symbloc link it as 'S99delete-auto-pseudonyms' into the 'user-create' and 'user-modify' event directories.
This script should (please test!) do this:
#!/usr/bin/perl -w
package esmith;
use strict;
use esmith::AccountsDB;
my $accounts = esmith::AccountsDB->open;
my ($event, $userName) = @ARGV;
$accounts->remove_user_auto_pseudonyms($userName);
exit (0);