I agree with all of it.
Single coat canines have trouble working in extreme weather, that's true. My dog gets hot in the sun if there's no shade relief and actually does better when it's cold. But only if she's moving/working/doing. If she has to be still, or down next to me for any length of time she's a shivering mess and will get vocal about how miserable she is.
I don't think their statement about training is accurate for obedience. Almost any Dobe can be trained to high levels of obedience. Protection and any action under pressure takes a different type of Doberman that is not nearly as common. But that would not exclude the average Doberman from doing SAR or any kind of detection/scent work. They ARE sensitive, and many are gun shy/noise sensitive, over-reactive and whine or bark when left on a long down or in a crate in different environments. All K9s have to have excellent nerves regarding these things - meaning indifferent and ignoring it all. The WAE test is a simple review of nerve type for household pet/sport Dobermans and if you can, go watch one and observe. The GSDs and Mals have much larger and diverse working lines to choose from, the Dobermans have evolved into mostly household pets with a tiny pool of working/protection sport dogs, most of which could not stand up to LEO standards. Again SAR and nose work would be the exception, but they are still tested steady nerve, going into tight areas, rubble piles, explosive noises things you would expect in a disaster area.
Health is the number one problem. It takes years to train and develop a military K9 and with it becoming more and more likely that the breed won't live to see 10 and most have health issues of some sort way before then, why would they be considered? I took offense of the video highlighting vWD as an excuse. That disease is easily tested for and can be 100% prevented by breeders in any given litter and Clear or Carrier dogs do not have any health problems related to it, so why bring attention to that? it's not nearly the problem that DCM, cancers and liver or thyroid diseases, non of which can be accurately predicted and all of which are common enough at age 7 or 8 to put off someone choosing a breed to be a lifetime investment as a partner in their career.
I totally agree with
@JanS about the pointy ears. That started after 9/11 and all the airport security and since these dogs were working around thousands of John Q Publics, many of whom may have had innocent fear of dogs in general the pointy ear shepherds were passed over for talented beagles and working labs since the didn't "look mean". Dobermans with ears and tails would probably be accepted, but even then red would be better than black for a less threatening look.
All in all, a Doberman in LEO or Military is pretty much a thing of the past. Always there are exceptions, but becoming really rare.