It doesn’t fit the spirit, because it doesn’t have the legal qualities of nullification. In particular, the prosecutor can choose to empanel a new grand jury and seek a new indictment on the exact same charge.
Edit: to be clear, the essential quality of nullification is that it’s the product of a contradiction between two unassailable principles in our legal system. Without that contradiction, which does not exist in a grand jury context, a juror’s decision is not nullifying. It’s just a decision.