"I don't get why PR prefers to declare #1 over declaring #2."
Ok, this time is pretty obvius why.
But let's talk about the first dichiaration. Switch beat GBA anyway, so why say Wii was the old record when it clearly was GBA?
Most likely because back then Nintendo's PR was hard at work to portray Switch as a home console that you can take anywhere, so consequently they compared its sales to previous home consoles.
The reason why it's so important to pitch Switch as a home gaming system are the software prices. If consumers perceived Switch as a handheld, they would be looking at a jump in software prices from $40 to $60 which is an increase that is unprecedented from one generation to the next. Buf if consumers perceive Switch as a home gaming system, then $60 for software is perfectly normal.