Here's what factcheck actually said, from the article:
You're missing the important part of the article:
The answer is that the term "guaranteed" is a weasel word — a qualifier that sucks the meaning out of a phrase in the way that weasels supposedly suck the contents out of an egg. It may sound to the casual listener as though this ad is saying that the benefits of all Medicare recipients are guaranteed to stay the same — and that may well be the way the ad’s sponsors wish listeners to hear it. But what the administration is really saying is that only those benefits that are guaranteed in law will remain the same.
There’s even a section in the new law (section 3601) that says: "Nothing in the provisions of, or amendments made by, this Act shall result in a reduction of guaranteed benefits under title XVIII of the Social Security Act" (the title that establishes the Medicare program). Section 3602 says even Medicare Advantage recipients won’t suffer any reduction of "any benefits guaranteed by law."
But here’s the catch: The extra benefits generally offered by Medicare Advantage plans aren’t guaranteed by law. They are offered by private insurance companies as inducements. The companies have been able to offer somewhat more generous packages than traditional, fee-for-service Medicare because the system pays them as much as 40 percent more per patient than it pays for traditional Medicare, according to the chief actuary. The average in 2009 was about 14 percent more, according to the most recent analysis by the nonpartisan Kaiser Family Foundation, issued in February. But the new law generally eliminates the extra payments in the coming years.
In other words, the ad makes a factually correct statement (guaranteed Medicare benefits aren't touched, even in MA plans) by actually referencing the protections written in the law itself. There's absolutely no way that re-stating the actual language of the law can somehow be a lie about the law.
FactCheck's premise, as I said, is that people might not know that the 24% of Medicare beneficiaries or so who are in Medicare Advantage plans might be getting additional benefits that aren't guaranteed. But the reality is that those people are getting significantly more money spent on them by Medicare than are the other 76% of Medicare beneficiaries. Believe it or not, Medicare paying for your gym membership isn't actually part of what you're entitled to for paying your payroll taxes over your working lifetime. That benefit, for that minority of beneficiaries lucky enough to get it, is
not guaranteed in law. Lots of benefits
are guaranteed in law and those aren't being touched (which, again, is what the ad says). However that per patient payment disparity that FC mentions is exactly what's being reduced under the law and that may result in some perks (that other, fee for service Medicare beneficiaries already have to pay for out of their own pockets if they want them) being eliminated from the Medicare Advantage gravy train.
FC bases its objections on how the statement "may sound to the casual listener," (by that they apparently mean an uninformed listener) not its actual truth content. But I have no idea how you'd explain these concepts to someone in a 30-second TV spot or why you'd even want to try.