The 41-year-old dad-of-three was referring to radio and TV presenter Myleene's exposé of emails she received from the parents at her seven-year-old daughter Ava's school.
In a sarcastic reply, Myleene slammed the 'bonkers' mums, who has asked for £10 donations to buy their children's birthday presents, and claimed Ava wanted a unicorn for her birthday.
A week later the head teacher of the £5,000-a-term North London school hit out at Myleene in a newsletter to all parents.
The head wrote: "No more parking on zig zags. No more blocking in the neighbours. No more unicorns. And as my granny would've said, if you can't tweet anything nice, don't tweet anything at all."
Now reality TV star Peter – who is dad to Junior, nine, and Princess, seven, by Katie Price, and one-year-old Amelia with fiancee Emily Macdonagh – has come out in defence of Myleene – but with a caveat.
In his column for new! magazine, Pete said: "I think what Myleene wrote was hilarious and I agreed with it, but she shouldn't have done it publicly.
He added: "I understand why the teacher said what she said but, then again, there was no need to do it so publicly. Two wrongs don't make a right."