I think the difference between Akainu and Zebra is that Zebra is considered a dangerous criminal, and a danger to the world in general, and was once on death row (even if it was by his own choice) The only reason he got out of prison was because the President of the IGO is his adoptive father.
I know his character was developed a little when it was revealed all the species he ate into extinction were dangerous creatures, it still didn't change the fact that he can be an asshole though.
This just shows that all of those countries were fearful of his release for good reason, and Zebra is still a criminal who happens to get away with what he does because of who he is. (other than them worrying about him affecting the price of food)
Other than that, I assume that the other three, and Zebra knew those building were evacuated thanks to Toriko's smell, Zebra's hearing, and Coco's sight, so they didn't make a big deal over the fact that he was destroying property.