Not slippery. At minimum, street names must match to have a chance to be "=*_link". Here, it is still called "Prince Edward Road West", it is a component of PER (currently "=primary") and we can give it "=*_link".

imo the segment does not feel like "internal road", because it brings traffic from outside the block to inside it. (True "internal roads" see east side frontage road of PER.) But if it is "internal road" then yeah do "=unclassified" or below.