Aren't advertising requirements that constrain subject matter effectively a mechanism for banning content?

One of the reasons given for rejection was:

Referencing topics such as: Paedophiles, Rapists, Murderers, Enemies of the state, Journalists, Refugees, Controversial opinions, People’s bedrooms, Police officers, Children’s headsets … is inappropriate and irrelevant to the average consumer’s experience with a VPN.

That doesn't seem to me like the sort of criteria that a rule-enforcement agency should be using for determining whether something should air. (For what it's worth, refusing to air this in the US would absolutely be considered a freedom of speech issue.)

It isn't the first time that the advertising requirements were used to chill speech. It doesn't matter whether there was a ban; what matters is whether speech was effectively prevented. "There is no God. Now stop worrying and enjoy your life."

As someone who isn't familiar with the UK advertising laws, is this https://en.wikipedia.org/wiki/Advertising_Standards_Authority_(United_Kingdom) what you mean?