I understand the quoted sentence differently.

I think it is specified for permanent residents (aka landed immigrants) of Canada. Only for the permanent residents under VWP, they don't need the nonimmigrant visa to re-enter the US.

So after landing, H-1B can't be used for revalidation, since the H-1B holder has changed the status to permanent resident of Canada. That's why the officer said that I couldn't enjoy both benefits. This makes sense since with a maple card, there is no record when that permanent resident enter Canada. If he/she doesn't need visa to re-enter US, it's difficult to calculate the length of stay in Canada.

I think many H-1B still use "Automatic Revalidation" to re-enter US, it's because of the US officer didn't notice his/her status changed to Permanent Resident of Canada.

What do you think? Thanks.