Maybe you misinterpret the meaning of deterrance and MAD.

The deterrance simply lies in that you threaten to take revenge.

Is it a problem - no.

Why you ask. 2 reasons.

First, you do recall we have an ABM system that can hit "evading" ballistic targets.... Its the Aegis Theatre Ballistic Missile Defense System (or some such). There are something like 6 cruisers at this standard of the Aegis system. You can bet if we send a carrier group toward China it will have one with them.

Second - they may have a system they think will work - on paper. But - did you notice they said that the sources USUALLY only talk about systems that are past the test phase. Its not been tested - because to test it, the chinese would have had to send up a missile on a ballistic trajectory, then have the dummy warheads hit a "target" area. Think our missile watchers are so asleep they would miss such a thing?

"Oh - china just launced a ICBM. Thats nice - I'm gonna go get more coffee. Its probably a test anyways. See you when I get back - maybe..."

Its a nice theory - but take the Shkval torpedo - we knew about it right after the test. And that test ground was a lot more PRIVATE than the wide open upper atmosphere.

That is not enough.

You threats have to be believed.

Potential enemies must believe that you would carry out the retaliation
threats, despite it being illogical and unethical to do so for the reasons
Kazuaki pointed out.

The MAD mechanic only appears and works when everyone believes
that everyone else follows the MAD mechanic (over and above logic
and ethics).

MAD has a fragile existence born of a kind of circular reasoning.

Fortunately, it isn't MAD that is the main deterrent against using Nukes
anymore. MAD was born when there where only two major nuclear
powers: The USSR and the USA (and a few smaller NATO members).
Both sides had enough weapons to ensure the total destruction of the
other side. MAD was the only option.

Now there are more Nuclear armed countries and none of them have
the capability to utterly destroy every single other nuclear armed
country. Even if several countries are destroyed and they do not launch
MAD counter attacks, there is a good chance that other countries not
attacked or not completely destroyed will get nervous and start getting
preemptive. There is a good chance nukes will fly your way, even if no
one takes part in a post-strike MAD retalliation.

Kill their satellites first and the missle is useless.

No, they must worry you. A revenge on a scale that does not worry you, may take place or not - but you would not care anyhow.

It's not a question of ethics. It's a question of fear.

Can you worry about threats you don't believe in?

If I don't fear them - no.