Answer:
Because the man was "Asian, Thai, or Vietnamese," we can assume nobody understood his language. Even if he did speak English, in his dying moment he might have been speaking in his mother language.
Or, perhaps, his words were difficult to understand because the wound was too bad and made him wobble.
Explanation:
This poem, published in 1988 as part of Hongo's poetry collection The River of Heaven, was based on a piece of real news he saw about an Asian man who had been accidentally shot in Chicago. Hongo dedicated it to him, "In memory of Jay Kashiwamura." The first answer seems more likely as the poem seems like a critic of the hardship that those who don´t speak English suffer in the US.