What happened in King's Landing was meditated with Blue, by the way. It is a part of Garland's plan, but basically, shit got fucked and a lot more people died than needed. The City Watch just got a Coup D'Etat'd the shit out of it, and now, Willas is at it's head, locking the city in. It's a pretty morally questionable thing, but in short, you can view it from either extreme, from either being an outright insult or just a peacekeeping measure to quell the capital. He'd be playing to anarchy, or chaos. Full Petyr Balish style. Or at least, if it's sustained, then it will work. It shouldn't have had any negative repercussions, but owing to the fact that Willas is running on urgency, you can imagine the capital as basically desending into total confusion. Kevan will likely be completely losing his shit when he awakes to a new dawn outside, and the City Watch are cleaning up bodies, demanding to see Willas and demanding to ask what the fuck is going on. It's had worse as there are dead people, and Willas isn't going to look good in any shape or form to anyone who dislikes Tyrells.