Hong Kong's appeal to mainland experts is aimed at achieving the widespread testing that helped underpin successful virus-eradication strategies in cities like Wuhan and Beijing.
One of the activists, American national Samuel Chu, announced "he woke up to reports he was a wanted fugitive" on Friday.
Germany's Maas described the election decisions as "a further infringement of the rights of Hong Kong's citizens".
The broad-sweeping law, which was widely criticised internationally, allows for life in prison for those China determines to have engaged in acts of secession, subversion and collusion with foreign forces.
The Global Times said the team was established at the request of the Hong Kong government, at a time where medical resources in Hong Kong are said to be overstretched. Some proposed "safe haven" visas for Hong Kong residents wanting to leave.
City elections now have electoral committee mechanisms in place that favor pro-Beijing candidates; pro-democracy protests in past years have called for universal suffrage.
Wang noted the Hong Kong and Macao Affairs Office of China's State Council and the Liaison Office of the Central People's Government in the HKSAR have voiced support for HKSAR government's decision, saying there are many examples of other governments postponing local elections amid pandemic.
Hong Kong leader Carrie Lam cited a worsening coronavirus outbreak in the semi-autonomous Chinese territory in delaying the elections.
The controversial security law is seen as undermining the "one country, two systems" framework that sees Hong Kong as governed separately from China - a key part of the 1997 deal that saw the United Kingdom hand over the territory to China.
Foreign Ministry spokesman Wang Wenbin told reporters that China has chose to suspend an agreement for the transfer of fugitive offenders from Hong Kong to New Zealand.