Harsimran Singh, a student of University of California in Davis, said he has travelled for the last two years with kirpan in full view and did not face any issues until Saturday morning.
"They do not say anything. They always wish me safe travels, and they continue on with their business they did not see me as a potential threat," Singh was quoted as saying by CBS news on Wednesday.
The sheathed blade is a sacred and religious item to the Sikh faith. However, the driver of the Amtrak bus, Al Smithee, was concerned at the presence of a weapon on the bus.
"I'm doing 70 miles (112 km) an hour down the freeway, and he slits my throat, and I crash and wreck, and kill five other people or on coming traffic. You don't know," he said.
Singh said he keeps the blade sheathed 24 hours a day as something that protects him from more than physical dangers. "[It's about] protecting yourself from evils, ideologies that would otherwise corrupt you," he said.
Symbolic or not, Smithee saw it and called police. They agreed that Singh could get on board if he stowed the blade. He declined the offer and scrapped the trip to see his family.
"For me, my faith is stronger to me that I wouldn't compromise it just for the happiness of somebody else," Singh said.
Smithee said the issues to him wasn't about religion, it was about rider safety. "I don't care who it was. If they have a knife sheath hanging down, it's a weapon.