After Moira went live on press conference telling the entire city about Malcolm's plan, why did Malcolm still go ahead with his plan and destroyed Glades? he couldn't have gone Scott free after that, even if he was left alive, he would be imprisoned for life, so he was not going to build anything on the one-third of the property of Glades that he had purchased. On the other hand, if he had not destroyed Glades, Moira's press conference would have become a false alarm, and Malcolm's lawyer could have presented in the court that there was no such plan to destroy anything and Malcolm would have remained a free man and Moira might have got jailed or sent to some mental institution.
SCPD captain not heeding to Detective Lance's information about imminent destruction of Glades is not as it happens in real life. Any public servant is bound by duty to play safe and minimize the number of deaths and then reduce the damage to property. So, even if Lance had got the tip from the vigilante, Captain is bound to make arrangement, just in case the tip were true. He doesn't listen to Lance, rather suspends him summarily, and doesn't do anything at all to save Glades. After Glades was destroyed, there would be huge repercussions for Captain and everyone, from general public to entire administration would seek blood of the captain.