There may be more going on with the Bernie Sanders than we currently know I suspect. The issue as relayed is not a game ender for bernie, and he has oodles of money and plenty of time to distance this before votes start being cast. But Jeff Weaver is a skilled strategist, and some of the language he used when releasing this news was campaign killing language, language that you would only use if you know the campaign is over. Momentum and staying relevant is critical at this stage and if you are intending to power through and compete you move to immediately contain the damage downplay the situation and project optimism. You do not "suspend until further notice" you pause the campaign appearances temporarily in an abundance of caution under doctors orders but look forward to getting back on the campaign trail in short order. Leaving the issue at an indefinite suspension and no timetable in a somber tone is not the move.
Maybe Jeff Weaver just royally screwed the pooch, but that would surprise me. Absent that, Bernie's campaign is effectively over and theres maybe more to it than the health issue that they described. My two cents.