I think the “negative” of talking about Bolton as a possible SoS is “that making the announcement too early subjects the candidate to an invasive media rectal exam, poking and probing to generate sensational news at the expense of the candidate.”
I think the “sensational news” is how Trump spends $0 a month on any ads, while Hillary, with all media support, still spends $40 million, despite being close to each other in the polls.