With the nomination of John E. Higgins Jr. to fill the remaining vacancy on the National Labor Relations Board, President Reagan has assured that the nation's principal union regulator will remain in the hands of political moderates well into the next administration.

The point has not been lost on the National Right to Work Committee.

The Higgins nomination, committee spokesman Clayton Roberts said, "is an openly hostile move against right-to-work supporters."

Roberts said the nomination "flouts stated administration policy, the Republican Party platform and President Reagan's pledge to defend the rights of America's working men and women."

The committee is particularly upset by what it calls Higgin's "hopelessly one-sided position" against the committee in a case before the Supreme Court.

Beyond the Right to Work Committee, however, Higgins appears to face little serious opposition.

Higgins is deputy general counsel of the labor relations board and has spent his entire government career with the board, first as a field attorney, then working up through legal jobs to his current position.

By most accounts, Higgins, a Republican, is viewed as nonideological and open-minded, unlike Donald L. Dotson, whose vacancy he was named to fill.

Many Republicans and Democrats considered Dotson, who was the labor relations board's chairman until his resignation earlier this year, an ideologue who tried to eliminate what he saw as the board's prolabor tilt.