No. Look at the definition of winopen2. It dups stdin and stdout to the socket pair prior to starting the child process, so it inherits the sockets as its stdin and stdout; it then restore the originals in the parent once the child is running:

sub winopen2 {
    my ($pid, $oldin, $oldout);

    my ($server, $client) = winsocketpair
    or return undef;

    open $oldin, '<&', \*STDIN or return ();
    open $oldout, '>&', \*STDOUT or return ();

    if (open (STDIN, '<&', $server) and
    open (STDOUT, '>&', $server)) {
    $pid = eval { system 1, @_ or die "system command failed: $!"};
    # print STDERR "error: $@\n" if $@;
    }
    close STDOUT;
    open STDOUT, '>&', $oldout
    or carp "unable to reestablish STDOUT";

    close STDIN;
    open STDIN, '<&', $oldin
    or carp "unable to reestablish STDIN";

    #printf STDERR "pid %d, fileno %d, stdout %d, stdin %d\n",
    #    $pid, fileno($client), fileno STDOUT, fileno STDIN;

    return ($pid and $pid > 0) ? ($pid, $client) : ();
}
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