The post performed a valuable public service, exposing unacceptable behaviour from a person in a position of power. But the government is currently in the process of passing a law which would make similar posts in future illegal.
The law is the Harmful Digital Communications Bill. Section 19 of the bill creates a crime of "causing harm by posting digital communication":
A person commits an offence if—
(a) the person posts a digital communication with the intention that it cause harm to a victim; and
(b) posting the communication would cause harm to an ordinary reasonable person in the position of the victim; and
(c) posting the communication causes harm to the victim.
For the purposes of the law, "harm" is defined as "serious emotional distress". TechLiberty's pointed out last year that this clause applied perfectly to the exposure of corrupt politicians, something which an ordinary reasonable person would think would cause them serious emotional distress. And it applies equally to exposing creepy ones as well. And no, there's no public interest defence. The kicker? The National-dominated select committee has increased the penalty for this offence from three months to two years imprisonment.
The message is clear: if in future you expose the Prime Minister as a creep using the internet, you'll be facing jail. So much for our democracy.