“Before Abraham was, I am” may simply be an emphatic statement of preexistence. And the crowd’s reaction proves what they heard, not what Jesus meant.

Both points are fair. The crowd picked up stones for blasphemy, which requires more than a claim to be old, and John deliberately echoes the divine I am of Isaiah 43; but reactions show reception, and John may be shaping the scene. The preexistence reading should be on the table as the alternative. Even on that reading, a man who claims to have existed before Abraham and whom the crowd tries to stone for it is not merely a prophet, and the cumulative pattern across Mark, Paul, and John is what the claim rests on, not this one verse.