Just trying to grab as much stuff as he could while he could get away with it. He saw the writing on the wall. Not too many jobs are going to require "hides in bushes" as a skill set, so get the fridge while the fridge-getting is good.
After they declined, the Journal reports that Spicer decided to bypass their response. He was reportedly seen by another staffer dragging the fridge down the White House driveway at approximately 8 p.m. The Journal described the researchers as ”surviving on Lean Cuisine frozen lunches."