It's a strategy in multiple parts; and one that normally avoids walking directly into unwinnable fights (these guys are evil; but they aren't stupid and are in a position where the margins are good enough to allow for a quite sophisticated apparatus that justifies its costs by preserving and juicing the margins):
What you will see provided openly are fairly vague, high-level, defenses of drug costs being high: lifesaving innovation isn't cheap, look at how far we've come in outcomes for X disease in the last Y years, biologics are so much more complex than traditional small molecule synthesis stuff so you can't treat generics as equivalents, etc. etc. These arguments will rarely be overtly false; though they'll be careful to avoid getting dragged into the weeds on off-message questions like "sure, that's all well and good; but how are all the same things true at less than half the price over in western europe?".
Then there's the class of arguments that they don't exactly buy advertising for, because they don't focus-group very well, but which are made more or less openly, though usually in specialized company like investor calls, and based on actual pricing data: this is where you'll get the "Our gene therapy for Ghastly Y-Linked Genetic Disease X will be $1.5 million; because current standard of care is over $100k/year in esoteric recombinant immunoglobulins delivered in impatient infusions; so really it's a win-win". This sort of argument will studiously ignore any questions of whether esoteric recombinant immunoglobulins actually need to cost so much as out of scope; and will treat the development and production cost of cool new gene therapy as irrelevant; the price is purely a question of what the market will bear based on what alternative therapies currently cost.
Then you get down to things like the PBM markup stuff described here; where you simply don't justify or defend the markups; but you structure the various contractual and ownership arrangements and the publicly visible price signals such that you don't have to. In some cases this is done through sheer complexity: Unless the guy at the pharmacy counter happens to be a sick investigative reporter who does a very specific flavor of story the odds are basically zero that they know anything useful about the web of ownership and contracts between the pharmacy, the PBM, the insurance company, the drug manufacturer and distributor, etc.
Then you've got the other sense of "defend": "gag clauses". You don't have to present a principled justification of something in order to defend it; you can simply conceal or impose it. If the pharmacy can get a drug for $30; but the PBM price is over $2k; it's often cheaper for the patient to just exchange money for goods and services as though they actually lived in a free market economy and pay $30+whatever it costs to keep the lights on at the pharmacy; rather than "the drug cost $2,200; your insurance saved you $1,800; that'll be $400". So you contractually forbid the pharmacist from mentioning that option.
In general, though, it's best not to think of American drug prices as being 'defended' in the sense of a thesis or an argument being 'defended'; but in the sense of a fortified position being 'defended': there will be some deliberately-visible arguments advanced, just as the military force that occupies a defended position will generally have a PR-friendly reason for their presence there; but the actual defense is not an argument; it's a complex and carefully constructed collection of mutually supporting camouflage, entanglements, information asymmetry, and so on.
