Maybe, if you could trick the server (64-bit FreeBSD) into connecting to sockets open on 32-bit FreeBSD machines. I can't think of any common services that would be susceptible to this (they would normally be susceptible to being tricked into opening other kinds of long-standing connections, too, which is just as good for DoS).
"...on 32-bit [systems]" is the operative part of his statement. I'm pretty sure 'tricking' a client into opening connections to a server is trivial regardless of TCP bugs.
