Oh, I get your point. Well, I can not say it with 100% certainty if something like that is possible. I never saw it with my eyes, honestly.
I have seen that brokers delay the execution of pending orders during the news—even a regulated broker.
But I guess if some broker does what you describe it will be a scammer. Because the regulated brokers take the prices from a couple of liquidy providers, and they take the average price. This is why most regulated brokers have very same prices.
I know that some of the worst scam brokers fake their prices to make their clients believe the TP was hit. This way, they ask them via phone to deposit more money.