Words in statutes have precise legal meanings, not the vague interpretations that get thrown in situations like this. Below is the statute that defines qualifications for grand jurors, mostly excluding felons and current/former office holders. The law does not provide for a change of venue because the majority of the county is of a different political party than the accused. Also, the rest of the statute you cited indicates that this process occurs upon motion from the DA, not the judge on his or her own and not the accused.
§ 15-12-60. Qualifications of Grand Jurors; Impact of Ineligibility
Universal Citation: GA Code § 15-12-60 (2021)
Any citizen of this state 18 years of age or older who has resided in the county for at least six months preceding the time of service shall be eligible and liable to serve as a grand juror.
Any person who holds any elective office in state or local government or who has held any such office within a period of two years preceding the time of service as a grand juror shall not be eligible to serve as a grand juror.
The following individuals shall not be eligible to serve as a grand juror:
Any individual who has been convicted of a felony in a state or federal court who has not had his or her civil rights restored;
Any individual who has been judicially determined to be mentally incompetent;
Any individual charged with a felony offense and who is in a pretrial release program, a pretrial release and diversion program, or a pretrial intervention and diversion program, as provided for in Article 4 of Chapter 18 of Title 15 or Article 4 of Chapter 3 of Title 42 or pursuant to Uniform Superior Court Rule 27, a similar diversion program from another state, or a similar federal court diversion program for a felony offense;
Any individual sentenced for a felony offense pursuant to Code Section 16-13-2 who has not completed the terms of his or her sentence;
Any individual serving a sentence for a felony offense pursuant to Article 3 of Chapter 8 of Title 42 or serving a first offender sentence for a felony offense pursuant to another state's law; and
Any individual who is participating in a drug court division, mental health court division, veterans court division, a similar court program from another state, or a similar federal court program for a felony offense.
If an indictment is returned, and a grand juror was ineligible to serve as a grand juror pursuant to subsection (c) of this Code section, such indictment shall not be quashed solely as a result of such ineligibility.