It's more like mcdonalds replacing Coke with McCola with your mcdonalds meal - you were already trusting mcdonalds for the food. But even that is a stretch since both are GPL2 and there's no current sign the plugin Automattic provide differs from the WP Engine one.
GPL is on both sides, nothing stops WP Engine doing the same and providing their own flavour of core with their plugin, if that's what people want. Of course that costs more than private equity just using Automattic's core for free.
To use your McDonald’s analogy, it’s like specifically ordering a Coke and McD’s secretly switching it to a McCoke without you noticing.
It seems the "perceptual framing" that is being engineered about this, that Automattic and its leader should be cancelled, is not about technical issues.
I’m not saying it’s right, but it’s just the kind of thing that one expects from American corporations.