From Singapore point of view :-
(1) We cannot forsake our friends that stand thick and thin with us.
Whether it is US - that have offer security to us since WW2 - thus we have to offer our base.
Whether it is Taiwan - that help us in offering space for us to train our troop since 1970s.
Whether it is China - that we have establish diplomatic ties in 1980s and we have help China in at least 3 Eco-cities.
Singapore rejection of Hainan base - is due to undue diplomatic pressures. Singapore initially accepted Hainan base.
Whether it is ASEAN or China - on South China Sea issue - where we need International Law - to ensure peaceful resolution of disputes. Else no Countries will respect laws to resolve disputes. All international contract, agreement sign --- can be rebuked, can be disavowed, can be annuled by muscles. Singapore has resolved disputes with neighboring Countries using this method - and result in peaceful, Win-Win outcome.
From China point of view :-
(1) Singapore training ground in Taiwan - pose a threat to China - because it reinforce Taiwan and unable to achieve China's pressure in squeezing Taiwan from diplomatic space, military exchanges and technological exchanges.
But Singapore already reinforced the "One China" principle - and does not deviate from this stand.
(2) Singapore adopt International law for resolving dispute - hurt China's interest and claim on South-China Sea. But China must understand that Singapore and all Countries interaction and integration in the World - is dependent on observing law, and International law to ensure law, order and peace. Else international order will be chaos and war, military confrontation will become the order of the day.
(3) China view Singapore port for US litoral naval ship and airbase for US P3 plane - as a threat to China.
But Singapore has no interest to compromise China security as Singapore has mammoth investment in China.
By hurting China, will effectively be hurting Singapore's interest in China. Moreover, many Singaporean Chinese has ancestral links with China and in fact have relatives in China.
It does not make sense for Singapore to help any States to launch military confrontation on China - where Singapore have more than business ties, but also ancestral ties.
Fed Up
Best
Ls