Plot hole: When the Avatars agree to rewind time they say that they can either put the world right or save Brody but not both. This doesn't make sense since they're rewinding to right when they put everyone to sleep, which is before Brody was killed.
Other mistake: When Phoebe gets the premonition to see all the loss, she sees the scene where Piper dies in All Hell Breaks Loose. Since time was rewound this event never happened in this timeline, and we're never given any reason to believe Phoebe would know this happened after the time reversal.
Deliberate mistake: When Zankou and the Charmed Ones force the Avatars to "put the world back" by rewinding time, in the first shot of people waking up note the Jeep in the backround. The problem is the words "Jeep Liberty" are on the spare tire cover in this shot, but in the previous episode "Extreme Makeover World Edition" that spare tire cover is all black because those words were edited out in two shots. The first shot is when that group of people fall asleep, and second shot is when they all wake up the first time. (00:35:15)
Other mistake: In the kitchen scene, Phoebe adds a mix to a pie crust but puts an empty crust in the oven. (00:04:10)
Answer: That was a mistake in the series.
Also, the episode is called 'Babies First Demon' and this alone tells us that it's Wyatt's first time in the field (so to speak) and as the sisters say, they've done a good job of clearing up their own magical messes so far. Nobody really knows how advanced Wyatt's powers are, or will become. That's why the cleaners appear, to nip things in the bud. The Cleaners didn't want to chance that the sisters could clean Wyatt's magic up, just incase they couldn't. Therefore intervening themselves, just in case.