It's .NET IR, not C# IR, but I agree. If the bytecode is not executed directly by the CPU, if there's a separate translation layer to convert that to machine code, then a user-friendly presentation of the bytecode is not an assembly language.
Most mainframes, like those from Xerox PARC, don't have any kind of Assembly, the first step of booting was to load the corresponding microcode execution engine.
(And most instructions correspond to 1 or a few uops in a straightforward way).