The Slovenian is the youngest driver to go back-to-back.
Slovenia's Matej Mohoric claimed the Tour's 19th stage, after police visited his team's accommodation.
Tadej Pogacar cracked during the 11th stage of the great race.
Mark Cavendish sprinted to his third stage win of the current tour.
Ben O'Connor climbed into second on overall standings.
The suspect had brandished a homemade cardboard sign reading "Granny and Grandad" in German.
Mass chaos ensued after the spectator clipped a rider with a cardboard sign.
Several nasty crashes have marred the opening three days of the iconic event.
Organisers are suing a spectator who was involved in one of two massive pile-ups.