Defense Secretary Caspar W. Weinberger said today that it is "absolute nonsense" for anybody to demand that U.S. strategic arms negotiator Edward L. Rowny resign because of a memo criticizing his colleagues.

"I would like to know what is so sinister about this set of talking points," Weinberger said of the paper that has come to be known in Washington as the Rowny memo.

Prepared for Kenneth L. Adelman, President Reagan's nominee as director of the Arms Control and Disarmament Agency, the memo reportedly includes a so-called "hit list" of arms control officials, complete with such characterizations as "out to lunch," "progress at any price," "got to go" and "a management disaster."

When the memo came to light recently, Rowny did not dispute its authenticity but said it was "prepared for me" as "informal talking points" which "do not represent my views."

Despite these disclaimers, some administration leaders fear that the memo, under study by the Senate Foreign Relations Committee, will complicate the effort to have Adelman confirmed by the Senate and undercut Rowny's effectiveness as head negotiator at the Strategic Arms Reduction Talks with the Soviet Union.

The memo has also drawn fire from Republicans and Democrats in Congress, with Sen. Gary Hart (D-Colo.) demanding that Rowny resign because of it.

Weinberger, continuing a concerted administration effort to minimize any problems resulting from the memo, talked with reporters flying with him from Washington to Portugal for a NATO Nuclear Planning Group meeting on nuclear issues.

"I have seen suggestions that Gen. Rowny might have to resign," Weinberger said. "That's absolute nonsense. He's one of the very best men we've got.

"He's one of the most knowledgeable; he's a man of very high moral principle, a very devout person, and I think the fact that he has been given some talking points, which he may or may not have used and may not have intended to use, about some comments about some people the duly-appointed head of his agency might find useful is the most normal thing in the world."

"I cannot see the slightest problem with a person who has a critically important position being given some talking points as to what he may or may not wish to do . . . ."

"For the life of me," Weinberger said, "I think there is so much desire to find something sinister in any piece of paper that this incident has been blown all out of proportion."

In Washington, a senior administration official, referring to the issue today, said, "The president is very high on Rowny."

Weinberger's remarks also may be part of a larger administration effort to persuade NATO allies that Reagan is doing all he can to negotiate reductions in medium-range U.S. and Soviet missiles deployed in Europe.

Weinberger will try to persuade fellow NATO defense ministers of this during meetings here through Wednesday. The major question is how to advance the medium-range missile talks and help cool the antinuclear protest movement in western Europe and elsewhere.

A senior defense official traveling with Weinberger was asked if Weinberger feels he is under pressure to propose an alternative to the president's "zero-option" plan. That offers to forgo U.S. deployment of 572 Pershing II and cruise missiles in Europe in exchange for the Soviets retiring SS20 missiles, most of which are trained on Europe.

The official said that neither he nor Reagan feels they are under any deadline to alter the proposal, even if this seemed advisable at some point because of lack of progress on the zero option. "There's no time pressure on the president," the official said.

He said that the scheduled recess March 28 of the medium-range missile negotiations is not seen as a deadline by the administration.

"There have been a lot of meetings and discussions already on alternatives," the official said of administration deliberations. "The president is thoroughly familiar with it. It's just a matter of what he ultimately decides" in regard to any changed instructions to the arms negotiators.

"A lot of possibilities are being considered," he continued, "including the idea that we have submitted a serious proposal and the other side has not, and therefore we ought to wait for a serious proposal."

Weinberger has indicated that he fears that stopping short of the zero-option goal will make it harder to reach it ultimately.

The senior official was reminded that NATO Secretary General Joseph Luns said in a broadcast for release today that the president's zero option is "not attainable." The official said Luns' remarks were not "conclusive."

"I don't think it's particularly significant," the official said. He said Luns was "adding up a lot of straws in the wind and trying to conclude from that the outcome of the negotiations" to reduce medium-range missile deployments in Europe.