I think he meant that because of the complexity of sshv2, it is much more likely that implementation will contain bugs/be compromised than the simpler sshv1. s

I think he meant that because of the complexity of sshv2, it is much more likely that implementation will contain bugs/be compromised than the simpler sshv1. sshv1 is less secure in terms of crypto, but not in terms of secure software implementation.