You may be right: although I'm not familiar with it. However, I don't think that you can credibly claim to cite the dancing in a commercial film released before the Golden Age as evidence to discount a style of social dancing in the 1940s.
I am not strongly of the Denniston party, and have no personal interest in proving her right or wrong. She describes, in detail, a way of dancing - and even if it only represents the way that a small group of broken-down old men ever did dance and were still dancing in the 1990s (and are now gone), it is still of interest.
She says, at various points in her text, that there was always a wide range of styles (but that they were mainly founded on a common technique) and that for all the inventiveness of the tango nuevo period, nearly everything that emerged could have been found in the 40s too, if you new where to look. I have no evidence for that either way, but given the time and effort that men put into the practica system, it would be remarkable if it were not so.
Inevitably, we all look to a model that suits us as being normative for the dance we adopt. For some, it is the dancing in their favourite milongas in BsAs, and they, in particular, burn with a missionary's zeal for the dance that they love. The trouble with that approach is that just around the corner, a very different style of dancing is normative for and is loved by others, and across town, everything changes again. Some of the better known guides to dancing in BsAs state the rather obvious point that every style under the sun is represented in that large cosmopolitan city, and when it comes down to it, the preferred style of any individual may only be found in a handful of milongas and be practised by so small a body of dancers, that in the worldwide scheme of things, it is no more relevant or normative than Denniston's particular take.
The same guide books take great pains to suggest that to find a certain style of dancing, care must be taken as to where you go, and the company you keep. By extension, you might reasonably conclude that the default style of tango is commercialised and predicated on the requirements and preferences of the tourist trade, that if you go to the wrong milonga, rather than the right one, the only people you will dance with are other tourists, or those caught in the tourists' net. Perhaps 99% of the teachers (who claim, perfectly truthfully, that they come straight from BsAs, have studied with a representative selection of the current 'greats') are peddling something other than the pure and only real tango danced by, perhaps, 250 people? If they wrote a book, under a pseudonym - let's say, Dennis Christianson, there'd be no shortage of candidates to shoot 'em down in flames.
I suppose, at least we no longer settle our tango relates differences with knives.