Yes, he is correct. So it is possible to incorporate the idea of nLockTime into script? For example:
1. The coin can be spent by 2-by-2 multisig with key E and key U at ANY TIME
2. If block height >= x, the coin can be spent by key U. The 2-by-2 multisig, however, is still a vaild way to spend the coin.
Validating that use of height is actually stateless in script would be horrific and more or less intractable. If script were designed so that there was a table of redemption options which had their own lock time then it could have been done... but alas.
It's no big deal in any case:
You are selling me your car. We decide to use a 2-of-2 escrow. But I'm afraid you'll hold up the funds if the deal falls through.
I compute the payment into the escrow and sign it. But I do not announce it yet. I also compute a transaction spending the escrow transaction and paying it all back to me with the locktime set some months from now. I sign that transaction. I give it to you (along with the txout its spending but not the whole payment). You can look at it and confirm that it is indeed unlocked until whenever, so sign it and give it back. Then I announce the payment into the escrow. You don't need height in scripts to get refund timeouts. QED.