Figure of speech. Professor MacHugh says that
Seymour Bushe would have been appointed to the judicial bench
long ago "only for... But no matter." His momentary lapse into
silence is an example of the rhetorical device of aposiopesis:
abruptly breaking off one's speech as if overcome with emotion
or reluctant to go on.
Latin rhetoricians coined the term aposiopesis
(AP-uh-SIGH-up-PEE-sis) from Greek apo- [an
intensifier] + siopan = to be silent. By lapsing into
silence an orator could, among other things, suggest that the
subject matter was powerfully stirring his emotions.
Shakespeare employs the device in this way in the funeral
oration scene of Julius Caesar when Mark Antony
feigns an inability to speak: "Bear with me, / My heart is in
the coffin there with Caesar, / And I must pause till it come
back to me" (3.2.105-7). Lear's emotional turbulence and
cognitive incapacity are more genuine when he sputters in
impotent rage at his daughters, "I will have such revenges on
you both / That all the world shall––I will do things–– / What
they are yet, I know not, but they shall be / The terrors of
the earth!" (2.4.279-82).
Richard Nordquist (thoughtco.com) cites some examples that
have less to do with emotional overload than with choosing not
to go into further detail. In The Case of the Gilded Fly
(1944), Sir Richard says, "'Could she have been shot from
outside, do you suppose, and the window––?' He indicated his
lack of confidence in the suggestion by resorting to
aposiopesis." In The Wizard of Oz, Auntie Em
says to Almira Gulch, "For 23 years I've been dying to tell
you what I thought of you! And now––well, being a Christian
woman, I can't say it!" And Homer Simpson tells Marge, "I
won't sleep in the same bed with a woman who thinks I'm lazy!
I'm going right downstairs, unfold the couch, unroll the
sleeping ba––uh, goodnight."
Professor MacHugh's pause is of this second sort: he decorously omits to specify that Seymour Bushe lost his chance at a judgeship and ultimately left Ireland because he had been charged with a sexual crime. Gifford quotes from a 23 October 1970 letter written by Colum Gavan Duffy, librarian of the Incorporated Law Society of Ireland: "It seems that a certain Sir ____ Brook and his wife were rather estranged, and that on a certain occasion the husband followed his wife to Dublin. He eventually found his wife in the room of Mr. Bushe and threatened to take proceedings against him. As there was no divorce in Ireland, these proceedings would consist in the tort of 'Criminal Conversation', whereby the husband would sue the alleged co-respondent for damages for adultery. It is for this reason that I understand Mr. Bushe left.... He also drank heavily."