They won't go to jail, period. No company owners never go to jail, kinda ever. This phrase is out of proportion. At worse they would have a fine.
Also still in the blog everything is words and very opaque like " We do this not only through technology and advocacy (Proton has contributed over $500,000 toward defending these values around the world)" : like where, what, when?
"There was no legal possibility to resist or fight this particular request." : I doubt very much unless Switzerland is a dictatorship in disguise.
"Switzerland generally will not assist prosecutions from countries without fair justice systems." : clearly not.