Billy Collins, Plagiarist?

Billy Collins has a poem in The New Yorker musing on Zeno's paradox:

Not long after we had sat down to dinner
at a long table in a restaurant in Chicago
and were deeply engrossed in the heavy menus
one of us--a bearded man with a colorful tie--
asked if any one of us had ever considered
applying the paradoxes of Zeno to the martyrdom of Saint Sebastian.

[...]
If, the man with the tie continued,
an object moving through space
will never reach its destination because it is always
limited to cutting the distance to its goal in half,

then it turns out that St. Sebastian did not die
from the wounds inflicted by the arrows.
No, the cause of death was fright at the spectacle of their endless approach.
St. Sebastian, according to Zeno, would have died of a heart attack.

Well, this is suspiciously similar to Tom Stoppard's explanation of Zeno's paradox, in his play Jumpers:

It was precisely this notion of infinite series which in the sixth century BC led the Greek philosopher Zeno to conclude that since an arrow shot towards a target first had to cover half the distance, and then half the remainder, and then half the remainder after that, and so on ad infinitum, the result was, as I will now demonstrate, that though an arrow is always approaching its target, it never quite gets there, and Saint Sebastian died of fright.

This is too strange to be a coincidence, right? Collins has to have somehow gotten the seed for his poem from Stoppard, doesn't he?

Maybe the dinner party actually happened as described in the poem, and Collins overheard "a bearded man in a tie" trying to pass Stoppard's idea off as his own original thought, but Collins wasn't aware of this, and wrote the poem in perfect innocence. Maybe the bearded man acknowledged that his Zeno-Sebastian speech was inspired by a line of Stoppard's, but Collins decided to leave that out of the poem. Or maybe there wasn't any dinner party, and the bearded man is fictitious-- a framework invented by Collins to hide the fact that he had really gotten the idea for his poem by reading or seeing Jumpers (or just by reading Stoppard's wikiquote page). What I like about this is that, even though Collins doesn't credit Stoppard, his poem still acknowledges the deeper truth: the Zeno-Sebastian idea is not original to Collins, he got it from someone else.

Some among us might simply call Collins' poem an "allusion" to Stoppard, or a work "inspired by" a line of his. And I might buy that reasoning if the Stoppard quotation were more well-known, or recognizable. (I mean, if Collins had written a poem playing off the idea of "beauty is truth, truth beauty," I wouldn't write a blog post excoriating him for plagiarizing Keats!) But, in my opinion, there is something not quite right about building an entire poem around an idea that another writer had, and then not crediting that writer.

Also, am I wrong in thinking that Stoppard's way of phrasing this idea is more snappy, more economical, more memorable, more, dare I say, poetic than Collins'? "Saint Sebastian died of fright" is much better than "No, the cause of death was fright at the spectacle of their endless approach. / St. Sebastian, according to Zeno, would have died of a heart attack." That's why I remembered the Stoppard quote, after all these years...