You're right. It's not on the admissable list.
I even called the 800 number in Canada, and spoke with a live person, and she confirmed that the 98 C280 can't be permanently registered in Canada.
In fact, the list is very odd. The 94 and 95 E320 are on the list, but the 1993 300E is not, even though it's the same car and same engine. The 86-92 300E's are on the list. Strange.
She's wondering if she can drive the car for two years in Canada, but keep it registered in California. She's planning on coming back in two years to go back to college.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".