This summary is not the rule. The rule text controls.
Judges can't just take any government job or position on the side while serving as a judge. They are only allowed to accept an appointment to a committee, board, or commission if it deals with the law, the court system, or how justice is carried out.
This rule exists to keep judges focused on their judicial duties and to avoid mixing their role as a judge with unrelated government work. For example, a judge could serve on a commission that studies court procedures or looks at ways to improve the legal system. But a judge should not accept a position on, say, a city parks board or a health advisory committee, since those topics have nothing to do with law or justice.
The goal is to protect the independence of judges and prevent conflicts of interest. If judges took on many outside government roles unrelated to their work, it could raise questions about their impartiality or create the appearance that they are too involved in political or administrative matters outside their proper role.