Also known as the "We must do something!" fallacy.
A type of extremist rhetoric where the presence a problem automatically justifies any measure that's invoked as a "solution", and the danger posed by the former automatically wipes away any concern about the possible dangers posed by the latter. A fanatical mindset of "anything goes as long as it might solve the problem at hand", overriding any principle of caution, any rational costs-vs-benefits analysis and any search for better alternatives.
Any attempt to bring attention to the possible risks is dismissed as irrelevant in the face of the present/imminent crisis, any appeal to moderation is regarded as "irresponsibility" or "laxism", any doubt or critical thought is framed as "denial", ultimately leading to social shunning and hatred against against everyone who doesn't conform.
The harm caused the promoted measures often turn out to be so huge to surpass even that caused by the very problem they were supposed to solve.