They wanted a chance to upset or offend and it seems it worked and then they hid behind the "we are men" mantle. If they were men or saw themselves as such they would not have enhanced their breasts. To look like women. There is no "We did not know" or "What breasts?...These things?" They deserved to get fined at minimum and their arses kicked by every Transwoman.
Personally, i think the majority of women, trans or ootherwise would have obeyed the law in the first place, so as not to cause a problem. It is possible these 'dudes' were trying to shock and knew there would be complaints which would have been dismissed once the cops realised they were 'dudes', but for whatever reason, it brought publicity (some unwanted) on the topic of transgender and laws of councils as far as exposure. I mean, some fucked up people even see pregnant women in bikinis as being obscene, and they aren't exposing themselves.