I didn't set out to redeem McGonagall but accidentally did here by filling out her point of view. Fiction is fun for putting forth thought experiments like this. What if you are very well intentioned, but still helpless? Normal world, that's probably okay most of the time. But when things are dire, that's not going to be good enough. I'm trying to avoid the typical trope that they are all neglectful, but also using her to better sell the idea of Snape as the better guardian by showing that well intentioned isn't enough. Taking action with what you have at hand is what matters.

:-) Snape is the Hermione of paying attention to everything happening around him.