If you commit crimes against people in country X, Y or Z, then you should expect to be brought to justice in country X, Y or Z, no matter where you're hiding out when you commit the crimes or when they are detected. That is only right and just under the fundamental tenets of international law, basic jurisprudence and common sense.
If they had been PRC citizens and their victims Taiwanese, it would be absolutely right and just for them to be extradited to Taiwan to face trial here.
If they had been citizens of the US, UK or anywhere else, and had scammed victims in a dozen other countries, it would be absolutely right and just for them to be extradited to whichever of those countries acted to secure their extradition, regardless of the relative merits of the legal and/or political systems in their victims' respective countries.
If I committed a telecom crime against a victim or victims in North Korea, Iran, or anywhere else in the world that anyone might consider to possess an unreasonably harsh or in any other way flawed legal system, it would not be for me - or whomsoever on my behalf - to bellyache against my being extradited to stand trial there.
It's as clear as crystal to me, and I don't understand why anyone would argue otherwise.
And what's with calling these people "white-collar criminals", with the inference that this makes their actions less serious and justifies their being treated with kid gloves? They are despicable criminals who prey upon gullible people and inflict great harm and misery on their hapless victims. Their crimes are every bit as serious as any crimes against property, and every possible effort should be made to apprehend them and, through whatever means of cross-border cooperation are available, to hit them with whatever sanctions of law are available when they are apprehended.
As long as the extradition process contains adequate safeguards to prevent it being abused for political purposes to secure the delivery of persons when there is no substantial evidence of their having committed the extraditable crimes of which they are accused, then there are no reasonable grounds for arguing against their extradition to the country where their crimes took effect, no matter where that may be. Is there any reason to believe that this condition has not been met in the case of these accused scammers?