Plot hole: According to the family tree viewed in this episode, Penny "Grams" Halliwell was born on 6/23/1937, and her daughter Patty, the Charmed Ones' mother, was born on 4/5/1950. In addition, Patty's father was born in 1930. So, according to this, Penny gave birth to her daughter at age 12, while married to a 20 year old man. That's quite outlandish, to say the least. (00:20:05)
Plot hole: It is stated Leo is born on May 6th, 1924. Yet he was in his 20's as Piper's ex-lover in his past life around 1924. It also stated that that is when he died and became a whitelighter but the war wasn't until 1942. He died shortly after that meaning he didn't become a whitelighter until after 1942.
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.