So I started looking online, digging about, and eventually found that despite about 35,000 webpages blissfully attributing this line to Mr Aligheri, this is actually a misquoted misquotation.
It seems that in a 1963 speech establishing the German Peace Corps, JFK claimed that 'Dante once said that the hottest places in Hell are reserved for those who in periods of moral crisis maintain their neutrality.'
It looks as though he was referring to a fairly famous passage in the Inferno which describes the cowardly angels and others who refused to take sides as being punished for eternity by being whirled through the air on the outskirts of Hell while being tormented by wasps and horseflies.
Now sighs, loud wailing, lamentation
resounded through the starless air,
so that I too began to weep.
Unfamiliar tongues, horrendous accents,
words of suffering, cries of rage, voices
loud and faint, the sound of slapping hands --
all these made a tumult, always whirling
in that black and timeless air,
as sand is swirled in a whirlwind.
And I, my head encircled by error, said:
'Master, what is this I hear, and what people
are these so overcome by pain?'
And he to me: 'This miserable state is borne
by the wretched souls of those who lived
without disgrace yet without praise.
They intermingle with that wicked band
of angels, not rebellious and not faithful
to God, who held themselves apart.
Loath to impair its beauty, Heaven casts them out,
and the depth of Hell does not receive them
lest on their account the evil angels gloat.'
And I: 'Master, what is so grievous to them,
that they lament so bitterly?'
He replied: 'I can tell you in few words.
They have no hope of death,
and their blind life is so abject
that they are envious of every other lot.
The world does not permit report of them.
Mercy and justice hold them in contempt.
Let us not speak of them -- look and pass by.'
And I, all eyes, saw a whirling banner
that ran so fast it seemed as though
it never could find rest.
Behind it came so long a file of people
that I could not believe
death had undone so many.
After I recognized a few of these,
I saw and knew the shade of him
who, through cowardice, made the great refusal.
At once with certainty I understood
this was that worthless crew
hateful alike to God and to His foes.
These wretches, who never were alive,
were naked and beset
by stinging flies and wasps
that made their faces stream with blood,
which, mingled with their tears,
was gathered at their feet by loathsome worms.
Kennedy's clearly overplaying his hand, and I'm not quite sure how we square this with Divine mercy, but I have to say, this sounds like a fine fate for those who'll stand by and watch while wickedness is afoot, rather than, say, an innocent student who just happens to be unfortunate enough to have been allocated a dodgy room.
Yes, and you thought being covered in bees was funny, didn't you?