Plot hole: The innocent who gets Piper's powers uses them to freeze Piper and Phoebe. But even though Piper and Phoebe no longer have their unique powers, they are still good witches; they were still able to scry, and we have encountered good witches on the show in the past who had no powers at all. And by the rules of magic within the show, good witches do not freeze.
Continuity mistake: In the second to last scene where Piper tests her powers on the lamp and Phoebe is cleaning, you can see Piper's bra strap when she blows up the lamp but when she turns to face Phoebe its covered. Through out the scene it's covered and exposed without her ever adjusting her shirt.
Plot hole: When the man and woman receive Piper and Phoebe's powers, the lady freezes the man and Phoebe due to fear, but good witches don't freeze, so if Phoebe froze (which she shouldn't have due to only her active powers lost) then why did the man? If he had Phoebe's powers then he isn't mortal and therefore should not freeze.
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.