I think what you have stated is more or less correct, and I can understand if you look at it from a very black and white point of view.
But keep in mind that 501st CRL's are canon and what the general public feels a specific character should look like. Most of the TD's in ANH had pouches and a pauldron, only one did not. This starts getting messy: if you watch the "new" SE versions, there are sandy / TK's standing in Tatooine with no pauldron or pouch but they are dirty!
You could say the same about ANH: why do TK's "have to have" blue tube stripes on their helmets, but Mr. No Stripes clearly has no stripes? But the CRL states you must have them as a TK. That's kind of a one off example. All TK's have to have them because most do.
Keep in mind that if you were attending an official 501st event, (eg: Rose Bowl parade or some LFL official event) you would likely need your TD to have pouches and a pauldron as per the CRL. If you are attending a con or other local event and your CO / SL says its OK, you could go in SWAT configuration and do the pauldronless / pouchless version. Don't get me started on the Biker Scouts and other characters that wear pauldrons at events...
Remember that SWAT is not an official designation of the 501st, it's a detachment based level of accuracy. It's also just for fun.