Why? Did 16-bit platforms change? I wrote a lot of code on 8080's and 8088's and never had trouble with bits then. Come to think, I did a lot of 16 bit word code on 6502's (8 bit CPU, 16 bit languages) as well. No trouble with bits, they have bit rotate as well as bit shift commands.
When I use 16-bit ints on Arduino that uses 16-bit addressing, what is the platform? Isn't that set by address length?
Note that I quoted someone else in that post and added a step I saw left out. But yah that RTC doesn't give a straight 10 bits, does it? The bits have to practically be mapped to the target. Good news is 32-bits only needs either 0x0000 or 0xFFFF added to a 16-bit solution.