Ewen Wilson and Milton Hertz are finally -- and officially -- on the job as high-level Agriculture Department officials this week because, as the senator from Kentucky put it, "you can say I freed the hostages."

The Senate late last week confirmed Wilson as assistant secretary for economics and Hertz as administrator of the Agricultural Stabilization and Conservation Service (ASCS) after Sen. Mitch McConnell (R-Ky.) dropped objections dating to last spring.

Under Senate procedures, a member can block nominations from floor consideration simply by placing them under a "hold," with no explanation required. Hertz and Wilson had been on the job on an acting basis while McConnell kept them on hold.

McConnell, who was angered by several earlier "pretty wrongheaded" Agriculture Department decisions on burley tobacco price supports, said he had blocked the nominations to "sensitize" Secretary Richard E. Lyng and other officials to problems of his tobacco-grower constituents.

The Kentucky Republican said this week that he felt he had "made my point" by blocking the appointments and by talking about tobacco several times with Deputy Secretary Peter C. Myers during the August congressional recess.

"We had good discussions," McConnell said. "There was no specific quid pro quo, but I felt that I had made my point . . . . I didn't think either of the earlier burley program decisions was justified."

The senator's displeasure with the decisions on tobacco ran so deep that he reportedly told President Reagan at a White House meeting that he would not support Reagan's veto of a controversial highway bill because of Lyng.

Lyng later told McConnell he would resign if the senator would vote to sustain the presidential veto. McConnell refused the offer and cast the crucial 67th vote that overrode the president.