Read the bolded in that quote:
Currently, about ninety percent of all criminal defendants plead guilty, and an unknown but substantial percentage of these defendants agree to testify against their co-defendants or co-conspirators in return for prosecutorial leniency. If the accomplice does not testify fully and truthfully, the prosecutor may refuse the leniency promised in the bargain. Courts sanction these "traditional" accomplice plea agreements and recognize them as a proper exercise of prosecutorial authority.
The bargain is only revoked based on grounds of truth, not because you testified in any particular manner. "Testifying against" in that sentence may mean that you are subpoenaed to testify in a particular case that is accusing someone of something. The agreement of the plea agreement is just to testify truthfully and nothing more.
The document you posted actually goes on at length to show what a plea deal really is. It is just encouragement to testify truthfully. That document says that prosecutors are officers of the court to encourage the truth, not to get people to testify in a certain way for convictions:
Prosecutors, whose duty is to seek justice rather than convictions90, should not place the desire for convictions ahead of the pursuit of unbiased testimony. Buying testimony with conditional leniency tips the scales of justice by inviting perjury.
Courts have rejected plea bargains which are contingent on testimonies that lead to arrests:
United States v. Bareshs is the only recent case in which a federal court deemed a plea bargain agreement so conducive to perjury that it tainted the testimony beyond any possibility of redemption. In Baresh, the contingent plea agreement provided the witness with a pardon and permission to keep assets obtained with his narcotics profits if his testimony led to the arrest and indictment of two specified defendants. If the testimony did not lead to arrest and indictment, however, the witness probably would receive a fifteen-year sentence even if he told the full truth. The district court for the Southern District of Texas concluded that the witness's devastating and totally uncorroborated testimony against a defendant whom the government had originally doubted it could indict was so unreliable that its admission violated the defendant's due process rights.
Courts have rejected plea deals that are contingent on the government's satisfaction:
The defendant in Dailey argued that the contingent accomplice agreements violated his due process rights because the agreements required more than full and truthful testimony. Two of the three agreements contained a promise for full cooperation in return for a recommendation of a sentence not to exceed twenty years. Furthermore, depending upon the value of the witnesses' testimony, the prosecution could recommend a sentence of only ten years. The agreement with the third witness consisted of a four-month stay of sentencing, the possibility of a further stay, and the potential for government support on a motion for sentence reduction. These last two benefits depended upon the value or "benefit" of the information to the government as determined by the prosecutor. The district court noted that the agreements required more than full cooperation by the witnesses because otherwise the provisions concerning the ten-year sentences and the further stay of sentencing would be superfluous. Therefore, the district court concluded that the prosecutor provided the witnesses with incentives to lie by conditioning further rewards upon the government's satisfaction.
Contingent plea agreements which elicit a particular testimony usurp the jury's role of determining guilt:
Because prosecutors already have the ability to obtain truthful testimony through traditional plea bargains, contingent agreements can only serve the purpose of eliciting particular testimony which the prosecutor wants to introduce at trial. The obvious danger of this practice is that the prosecutor ignores the principle that all persons are assumed innocent until proven guilty and instead usurps the jury's role of determining guilt.
When the prosecution makes a plea bargain agreement, they are just guessing at the extent of the witnesses' knowledge:
Because the prosecution does not know the extent of a witness's knowledge, the prosecutor must make a subjective decision whether to confer or withhold the benefits of the bargain.
It is wrong think that a plea deal means that someone has "flipped" against someone. The plea agreement is merely meant as additional encouragement to tell the truth, which again you are already required to do.