Scores were tight all the way down the line at the 2017 Worlds. If you go back & watch it--which, sorry, I am not up for, LOL--you will see disappointment when the scores come up from pretty much the bottom teams up through the top. Happy faces were in very short supply by the end of that competition. Same at Skate America last season, which he also called. Not particularly this season, though, where he was the AT. And definitely not at the 2016 Worlds where scores soared during the FD and he was also the AT. It depends on the mix of both the whole tech & the judging panel, and the performances of the day.
"No one" statements are like "Never" and "Always" in figure skating. There is no such thing. (Zhulin & Shpilband alone have always been quite happy to dispute this one, being such unbiased observers, of course

). P&C went into the 2017 Worlds having lost the SD to four teams internationally that season, btw: Virtue & Moir, the Shibs, Bobrova & Soloviev, & Cappellini & Lanotte. This season they have only had one outing in international competition, an at-home event where their closest competition did not even qualify for Worlds last season and the next closest finished ninth at the Olympic Games. We're really only assuming that P&C can't be challenged in the RD because of last season, the scores in that one competition, and because we know how competive Sinitsina & Katsalapov have been with most of the field this season (though their scores have been more competitive in the free). It's a well-educated assumption on our part, but it's an assumption nonetheless.
Note: Out of curiosity, I went back and looked at the scores from 2016-17 IDF and the 2017 Worlds. At IDF, P&C outscored Hubbell & Donohue by 9 1/2 points in the SD. At Worlds they outscored H&D by 0.36.