When I saw the picutes, at first I was like "well hell, just wipe it down and be done with it". I didn't see any scratches and dirt will wipe off just fine, along with the blood (using gloves, of course)...
BUT...
...the part about him not knowing what the hell he was looking at and not using the proper documentation to educate himself could've resulted (and still MIGHT!) in something much worse than a busted CD drive. Although Apple didn't send him directly, he DOES do work for Apple per contract, so he's essentially an Apple representative. The new iMacs are new enough to where most technicians sent out this month may have issues getting familiar with the machines physically, but at the very least, he should've been referring to the proper documentation.