Sam lashed out at Spock during the Peregrine incident, when the Gorn were actively threatening them. It was his fear and panic, though, and the incident seemed brushed off afterwards.
Unless Spock was referring to that when he had to be restrained in the meeting over him needing to clean up after himself.
Back on the topic, it’s a double-edged sword, really, because sure, now there’s more of a sense of tragedy in Sam’s death... But that’s also because now he’s actually a character who has a personality, a reason for us to care about his fate. The reason he was originally played by Shatner wearing a mustache was because he was only appearing as a corpse, he didn’t really matter. Now he actually is someone who we as an audience can feel the tragedy of his death because we have an idea of who he was and his relationship with Jim.