When someone’s chest wall muscles are paralysed they cannot breathe and they die very quickly. Whatever the cause of this the first step is to get oxygen into their blood by assisted breathing. At the scene, in an emergency a rube an be passed down the mouth and a manual pumping of air is carried out. If the paralysis is prolonged, as in the case of say a nerve agent, it becomes inefficient to continue to do this. A ventilator is then used, a machine that intermittently pumps oxygen into the lungs. A tracheostomy is necessary for a number of reasons as it is more efficient and associated with less problems. This part of the story cannot be disputed.
As to the rest of the theory I find that it introduces more difficulty in explaining. Motive wise I am not sure that Nulia Skripal would have done that given that it would be very upsetting for the grandmother. Yes their are cultures where ‘honour killing’ because of the stain on the family is practiced but I am not sure it is that strong in Russia. Moreover honour killings are usually a male macho thing although in some cultures women may also be involved in planning.
Whatever the motive and whoever did it we still remain with the question ‘what was the poison used’. The elaborate story about novichok is the bit here that suggests a state actor or at least a higher organisation able to elaborate further and manage the narrative. The accusations against Russia and out very soon after tge event and before any facts were verified and were done by a master liar who can mumble nonsense and be believed as we have seen recently. Remember also that nearly at the same time another Russian was also murdered in England. It not much fuss was made. Why did this receive such a high profile and the other didn’t suggests some manipulation. Other events such as the miraculous presence of the army’s chief medical officer at the scene, the lack of any other person at the scene being contaminated etc. Point out to one direction. Have you read tge blogmire? It is tge site to go to for detailed information and analysis.