Interesting. It may be a thing on paper though I have never seen it in practice. Technically, if you are passing through a park on a hwy without an alternate route (like the Banff/Jasper corridor) you do not need a pass. That's why there is a lane that bypasses the west bound entrance at Canmore. Coming east there isn't even a kiosk on the road itself (you have to pull off with minimal signage). I suspect a cyclist could be thought of as thru traffic like cars and trucks (which they are), just a little slower.
I have also arrived in Jasper twice now by train with my bike to start tours southward and there was no mention of passes. You might think if it were a real policy they'd have some form of collection at the station. It might be a case of a rule on paper but not practically enforced aka don't ask don't tell.