You are making two points:
1. You advocate and demand PRC to intervene foreign country's domestic affairs on behalf of foreign nationals of Chinese heritage, including your own country (in case of Singapore).
2. You take Etheopian Jews as a "good" example.
My thoughts:
The first point will do more damage to people you want to protect including yourself, because you are alienating yourself with your other countrymen (Indonesian, Malay or Indians). It does not matter where you claim your heritage. Remember China is not your home anymore some long time ago since your ancestors left the territory of Qing dynasty.
The first point does NOT help your cause in the mind of PRC, nor mainland Chinese, precisely because of your complain and condemnation of their "inactivity". One can not expect sympathy for other people by condemning them, not even your own brothers. Slap your brother in the face on the street and see what happens later when you are in need of help.
The first point also demonstrate that you expect privilege of ethnic Chinese than other citizens. That is colonialism in nature, no difference from the European colonialism in Asia, Africa and Latin America. Are you in support of colonialism of your own but "hate" colonialism by others? You have to answer the question first before continue any further with your demand.
The second point is irrelevant. Israel did NOT exist before 1945. All early Israelis at the foundation of the state of Israel are citizens of various countries. The state made it a law that grant any Jews to be eligible to Israeli citizen. The Ethiopian Jews are as much Israeli citizen as the Jews in 1945 so long as they choose to declare so. The Israeli government was simply rescuing its own citizens residing abroad.
The situation is similar to any foreign born person to Chinese parent(s) who automatically received foreign citizenship by place of birth. These Chinese are legally Chinese citizen from their birth so long as they make the claim before the age of 18. This is in the law. PRC would protect them as much as Israel protected those Ethiopian Jews in 1991. And China has demonstrated that will and capability in Libya in 2011.
91 chartered Chinese flights. 35 chartered foreign flights. 12 military airlifters. 11 chartered foreign sea ferries. 5 Chinese merchant ships and one naval frigate. 35860 Chinese citizens and 2100 foreign citizens from 12 countries.
I also want to clarify one thing about your "China abandoned its daughters". At the 1950s, SEA ethnic Chinese were given the choice of claiming either Chinese citizenship or citizenship of residing countries when these countries gained independence. The ones who chose Chinese (PRC) citizenship were repatriated to mainland China, about 600000 as I remember. I had one school mate being one of them. The ones choose to stay are pro-KMT, they choose the citizenship of the host country, I don't know if they could have chosen "citizenship" of ROC. Either way most of them are suspicious of PRC, or outright hate PRC. Now I ask you who abandoned whom? Why don't you call "ROC" abandoning their own loyal citizens?
It is always a tragedy when people suffering regardless their political loyalty, BUT the cause and responsibility MUST remain clear and just.