Question in OP. It’s understood that “suspending” a campaign means the candidate is dropping out of the race - they’re not going to “un-suspend” it at some point and start trying to win votes again.
Is there some legal/traditional reason behind this verbiage?
IIRC, it’s about fundraising – if a campaign is merely suspended, then the campaign can keep the money it has raised (for some future purpose, which might be another political campaign for the same candidate) – if the campaign ends, then it has to do something with the money.
Is it also an issue of delegates? Let’s say Carson announced he was ending his campaign. Wouldn’t he be obligated to release his delegates to another candidate? By just “suspending” his campaign he hangs out to their commitment to him and has them for whatever political leverage they’re worth.
Basically, candidates that end their campaign can only raise money for paying off campaign debt. “Suspending” a campaign means that the candidate isn’t actively campaigning, but hasn’t ended it.
There’s also always the possibility that some candidacy-ending disaster (death, dead-girl-or-live-boy, etc) befalls the front-runner, and they might be able to get back into the race. Unlikely, sure, but if it doesn’t cost you anything to prepare for the possibility, you might as well.