Yes, how a ventilator is powered is a direct and in-your-face comparison, but we shouldn't forget that all the equipment itself is oil based (plastics etc...)
I think those who support power alternatives are the first to admit that what we currently have has worked well so far and they are only too aware of the oil based sources things come from. Even so, they'd likely choose to use current power sources despite the problems that concern them because for now, that's all we have and now wouldn't be the time to switch to renewables, (which is what the original rather obvious question was).
I'd also guess, they'd be the first to recognize that although alternatives need to be found, there are more immediate concerns to focus on rather than arguing about it or trying to score easy points for ones side of an issue during a pandemic.