I don't know were they get 43 days. The most a federal employee can get is 8 hours per pay period or 26 days a year. All federal employees get 4 hours of sick leave per pay period or 13 days. Most accumulate sick leave for when they really need it. The only way to get more annual leave is time off awards or other leave categories such as military duty, jury duty, etc.
Most workers get 6 hours per pay period...so closer to 20 days per year, plus the sick time. I can't vouch for all Feds, but I certainly don't get the day off on Federal Holidays...nor do those I work with.
So the truth is somewhere in the middle...as it generally is. Yes, the Fed is quite fair in giving a reasonable amount of leave time...more than the private sector. However, its greatly overstated by articles such as the one cited above. Honestly, I believe 20/13 would be a fair allocation at any and all workplaces...to me, that's a much more important issue for "labor" than is a 15$ minimum wage.