Frankly, you can't just come into a site and tell people they should change a habit and standard acronym term that has been in place for YEARS on MULTIPLE detailing sites. So again, I'd say that reading, and common sense, are very important here. That is, reading to discover the definition of the term, and common sense to dictate that whenever you see "PC" without a number specified, they mean the DA machine. Usually a specification is only made when it ISN'T the DA being referred to.
And also, I'm hoping you've realized this by now but the PC7335, 7336SP, and 7424 are totally interchangeable, because aside from the factory accessories included with each, they're all the exact same machine. This is another fairly common mistake that new members make; constantly asking "which one is the best?" and insisting that the machines are totally different. Again, some reading helps to solve this misconception. In fact, some of us refer to our "PCs" when they aren't exactly a PC. My polisher is a Meguiar's G-100A. If I didn't specify that the G100A is actually a re-labeled Porter Cable 7335, most would again think it a totally different machine.
So really, "PC" is a catch-all phrase that, unless otherwise specified, denotes a DA polisher.... and it's a term that has been in use for many years by a large number of us on a large number of detailing sites. One person complaining isn't going to break that habit, I can guarantee. :howdy