For someone to deliberately obstruct scientific research on such a deadly and mysterious disease such as HIV over something as petty as a 'grudge' suggests a serious problem with that person's entire character. This kind of action was malignantly selfish and could have forestalled important research and the development of treatment for victims, something that the scientist should have reasonably been able to foresee.
He should be criminally prosecuted because his actions could be responsible for the deaths of many people. Because of his actions the research on aids may have been slowed down for several decades. The link between what causes AIDS and the people who get it could have been found much sooner.
Yes, I do believe that a scientist with a grudge that changed the samples of a man suffering with AIDS should be criminally prosecuted. As a scientist it's your duty to provide data that is not manipulated in any way. This data in particular could be life saving for many people.
The scientist in question should definitely be prosecuted because he purposely changed the samples. I would be more understanding if he did it by mistake but no scientist has the right to mess with samples, especially in studies of diseases. The treatment for AIDS has come a long way, but if that scientist had followed protocol maybe many more lives would have been saved.