Originally Posted by
TheCrimsonKing
Go back and read it more carefully. In sections C & D it doesn't say "commercial pilot may ONLY log flight time obtained in blah blah blah ..." it says "commercial pilots may log..." You can still log legal SIC time towards your ATP, but these paragraphs are also saying you may log time in additional ways (such as a part of a PDP or as a flight engineer time). I believe it was added because pilots were logging SIC time in single pilot airplanes which wasn't legal.
Even that is perfectly legal if the SIC is required by regulation/operating rule. There's a legal interpretation that IFR with Px with an autopilot is legal to log if the autopilot is not used for the flight, even when the operator has the autopilot in lieu of SIC Ops Spec. I can dig it up if anyone wants to see. There's also the 135.267 rule that requires an SIC for 10hr flight days. One would be advised to write down the circumstances, not just the time, in their logbook, but there are definitely multiple situations where SIC in 135 can be logged, without PDP. PDP just extends it to nearly all situations.