Doesn't a good soft fork signaling mechanism along with an activation warning system for non-upgraded nodes (i.e. BIP9, or even block version ISM for that matter) essentially fix this? I don't quite get why this should be an issue.

On December 17, 2015 10:52:39 AM PST, Jeff Garzik via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
>On Thu, Dec 17, 2015 at 1:46 PM, jl2012 <jl2012@xbt.hk> wrote:
>
>> This is not correct.
>>
>> As only about 1/3 of nodes support BIP65 now, would you consider CLTV
>tx
>> are less secure than others? I don't think so. Since one invalid CLTV
>tx
>> will make the whole block invalid. Having more nodes to fully
>validate
>> non-CLTV txs won't make them any safer. The same logic also applies
>to SW
>> softfork.
>>
>
>
>Yes - the logic applies to all soft forks.  Each soft fork degrades the
>security of non-upgraded nodes.
>
>The core design of bitcoin is that trustless nodes validate the work of
>miners, not trust them.
>
>Soft forks move in the opposite direction.  Each new soft-forked
>feature
>leans very heavily on miner trust rather than P2P network validation.
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>bitcoin-dev mailing list
>bitcoin-dev@lists.linuxfoundation.org
>https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev