Well, yes, but you cannot do any useful math on months with that fact. Late in January, plus one "month", gives you early in March; early in July, plus one "month", gives you late in July. I can't imagine what useful intent could lead to this code being correct.
I expect they had to write something that looked good to meet the deadline, even if it was completely broken.
One minute is 60 seconds by definition. Minutes with more than 60 seconds are just one (hacky?) way to support leap seconds.