My paranoia always gives these people too much credit, but I suspect that May is being forced (more by the situation than her incompetent party enemies) to take the fall for this one so that whichever fucker takes over the Tory party can try to distance themselves from it.
She's wearing that haunted look all the time now. It first started after Manchester (where she definitely knows she had a role in that) and has continued through London Bridge and now to Grenfell. She is utterly broken and is just trying to hide but her party won't let her go.