Like with the previous question, albeit this being from a different source, Betts defines "strategy" narrowly to mean
a plan for using military means to achieve political ends.
Thus mere MAD deterrence is not a strategy in this sense because you never intend to fire those nukes offensively (as first strike) to achieve some political goal.
You get bewildered comments though because this (Betts') is hardly the common sense of the word "strategy". To quote a relevant bit from the other author you mentioned in the other Q, L. Freedman:
The origins of the word ‘strategy’ lie in the Greek strategos, meaning the art of the general. The
word returned to the European vernacular in the late eighteenth century, just in time for the Napoleonic Wars, but it was defined largely in military terms, as military thought was fixated on battle. Strategy was about getting
into the best position for a battle; tactics was about how it should be fought. By the twentieth century it was becoming harder to avoid questions of policy, covering peacetime preparations for future wars, including
alliance formation, the purposes for which they might be fought, and the mobilisation of all national resources, economic and political as well as military, to win them. The relationship between military means and political
ends was captured during the interwar years by Basil Liddell Hart—‘the art of distributing and applying military means to fulfil the ends of policy’. It was non-committal about how military means were to be distributed while stressing the role of the political sphere as the source of strategic objectives. It also maintained the connection with military means. This is why Liddell Hart’s definition still works, even in the nuclear age. The difference that nuclear weapons made to the concept of strategy was to turn the focus away from war-fighting to war prevention, and to forms of coercion and intimidation, including deterrence, as well as crisis management and arms control. [...]
Eventually, nuclear weapons became more powerful, more numerous
and, crucially, possessed by more than one nation. New concepts and
approaches developed in an attempt to come to terms with the possibility
of a war in which the use of the most formidable weapons available would
mean, in all probability, that it would be catastrophic for all concerned.
Could any useful purpose be served by employment of devices which
invited discussion using words such as ‘holocaust’, ‘doomsday’ and
‘Armageddon’? And could any employment of nuclear weapons be sufficiently
deliberate and controlled to ensure that political objectives were
met. At issue has been whether a ‘nuclear strategy’ is a contradiction in
terms. To the extent that there has been an effective nuclear strategy thus
far it has depended on non-use, by deterring major war and helping to
hold together alliances. The most intense debates over nuclear strategy
took place during the Cold War but though that ended many years ago the
weapons remain, ready for use. Behind the question of whether strategies
based on non-use still have a role to play is the even larger question of
whether it is possible for the habit of non-use to be sustained. There has
been no use of nuclear weapons since August 1945. It is an impressive
record, but is it one that can be sustained indefinitely?
As you can see, he is mainly talking about the situation where both sides in a conflict have nukes, but he also mentions one when that was not the case, and ponders whether that might be repeatable.
Outside of a peer adversary situation, this assumption that nukes are not a strategy (even in this narrow sense of Betts') is clearly false as the US did fire nukes on Japan, and forced them to surrender, ending WW2, thus achieving a political goal.