Weld is pro-lifer repellent, including libertarian pro-lifers and pro-lifers who are leery of Trump.
Weld does not have a libertarian aura, his Democrat opponent in the ‘80s, John Silber, was actually more conservative on most issues, including government regulation.
Johnson himself wasn’t much of a draw last time. Throwing in a Massachusetts white show Republican who couldn’t even get voted to an Ambassadorship after the folks he offended as governor tels us about him.
They’ll draw as much from HRC as from Trump. They might evendraw some people willing to vote for the Republican underticket. Mostly a cipher, and a vanity play.
Regarding ambassador:
In July 1997, Weld was nominated to become United States Ambassador to Mexico by President Bill Clinton. His nomination stalled after Senate Foreign Relations committee Chairman Jesse Helms refused to hold a hearing on the nomination, effectively blocking it. Helms was also a Republican and their party held the majority in the chamber, but Helms objected to Weld’s moderate stance on social issues such as his support for gay rights, abortion rights, and the legalization of medical marijuana.
https://en.wikipedia.org/wiki/William_Weld#Ambassadorship_nomination_and_resignation
i.e., libertarians versus conservatives