The temperature checks fall into the category of biosecurity theatre. They are useless since the virus has a long latency period (time from infection until symptoms present) and it is transmissible during the incubation period ie, before fever or other symptoms develop.
Seriously, its too late now to shut the door anyway owing to the sheer number of ex-China passengers allowed in already. The virus is out there, but the math says that we in the west are lagging the Chinese experience by about seven weeks.