think your logic might be incorrect.
When you rotate 6A to become D4, the hi-bit of 6A is clear, which rotates into the carry.
The XOR with 79 does not affect the carry so the carry is still clear.
Lastly when AD is rotated, the hi-bit is set and goes into the carry and and the carry (which was previously clear) goes into the lo-bit, so the result is 5A, which is correct and the carry should now be set.