Well, yes. American films obviously have been soft on China because they've been desperate for access to the Chinese market. You don't bite the hand that feeds. In a similar way, if a significant amount of film production moves to the UK, it's likely that criticisms of the UK would be more muted. In the long run, this creates a national security threat when our media is inundated with non-neutral messages about other countries that are not acting in our best interest.
The easy way to see this is to reverse your lens. We've been the beneficiary of soft power from Hollywood for a century. It'd be ridiculous to lose that power without at least trying to preserve it.
> if a significant amount of film production moves to the UK, it's likely that criticisms of the UK would be more muted.
Have you watched British television or movies sometimes? They're not exactly sparing their country from criticism .. E.g. (the original) House of Cards, Not the Nine O'Clock News, etc.
The other country you mention, China, is a better match. But is that the kind of society that the USA wants to be?
Are you intentionally missing the point? Our films made in the US are already neutered from a free-speech perspective because we're chasing opinions that are politically correct in China. We don't want to worsen that by bending to every foreign tax break. We should be making unapologetically American movies, and if foreign consumers still watch those movies, all the better. But we shouldn't be writing these to a lowest common denominator of politically correct speech. It's how we've arrived at a point where all we produce is Marvel slop.
There's some point in that, although certainly not all US movie companies are self censoring in favor of China. Also, if the goal is to prevent chasing Chinese opinions, why not specifically target China?
Or are countries like Canada or the UK also seen as part of "a concerted effort by other Nations"?
The easy way to see this is to reverse your lens. We've been the beneficiary of soft power from Hollywood for a century. It'd be ridiculous to lose that power without at least trying to preserve it.