You talk about logic, but you aren't actually displaying any. Just because, for whatever reason, Ineos gave him the benefit of the doubt in the summer does not - logically - infer that they still think he's the bees knees, or even that they thought that at the time. Logic suggests that they are highly doubtful about him given that we know they have sounded out multiple managers, and given Ratcliffe's distinct lack of public backing for Ten Hag when specifically asked about him. I agree that the list of possible replacements has dwindled, and I also agree that in an ideal world they would have pulled the trigger during this last week - but I genuinely doubt that they are satisfied with the current situation and are prepared for that to continue. United do tend to have an infuriating tendency to stick with managers till the bitter end, but often the situation becomes obviously untenable for all concerned - like I say that point could come at the weekend. If he does manage to keep limping on until the next international break doing just enough but not showing a marked improvement then my guess is they will sack him then.
It's the notion that Ineos will be happy to see this continue for a whole season that I find hard to believe. Similarly the comments that I've read about Ineos not wanting to spend money on sacking him - like, they've spent over a billion on buying a 25% stake in the club, I serious doubt that a few million quid is going to prevent them taking action if there is no sudden (and sizeable) upturn in results.