What I saw was Clark standing up for his decision, and felt he was being strong here not letting Lois get away with her accusations.
He wished her use of her nickname for him gave him strength, but instead the tone in which she used it reminded him of how she once used it as an insult. “I’m sorry, Lois… about a lot of things…” he said, trying to find the words in his muddled head to make her understand what he was going through without having to speak of the incident itself.
Clark is not thinking clearly from the residuals of the torture. He's having trouble finding the words and quickly finding a suitable reply to Lois's temper.
I didn't see Clark as being whinny or weak (other than the understandable weakness from the torture of kryptonite and that video). He's in physical and emotional pain. His reluctance to deal with this
now is totally consistent with not being physically or emotionally able to cope with the added stress, and does not mean he can't deal with it later.
Despite Lois yelling, pulling him out of the sun (she obviously knows he need to be in the sun to heal) and exposing him by removing his sunglasses, he calms her down and tells her he loves her. Which shows a quiet strength of character in Clark. Lois's impetuous nature is shown well here, unfortunately adding to Clark's pain. And consistent with Cannon S1 Lois.
