Proteins as small as Neutrons!

In the Feb 27 issue of Forbes Magazine, they have a quick, relatively harmless article about a doctor who thinks we should spend more time and money on healthy lifestyles and preventative medicine over, say, classic cancer research.  However, toward the end of the article, this little zinger is in there:
"The trouble is, tracing proteins is hard to do - they are the size of a single neutron."
Huh?  Would the editor let a phrase like "The Declaration of Independence is a phrase shorter than a sentence" get by?  'Cause that is a less egregious error!

Interestingly, they fixed the statement on the version online (apparently after someone commented on this after the original posting).  Now it reads, a bit more reasonably:
"The trouble is, tracing proteins is incredibly hard to do -- they have to be examined at the level of a single neutron."
I assume they are referring to tracking isotopes which can differ by as little as one neutron from isotope to isotope.  However, isotope spotting is generally not thought of as being done at the neutron level - rather you just mass the whole atom and infer the extra neutron that way...
Here's the link to the fixed article:
http://management.fortune.cnn.com/2012/02/17/david-agus-end-illness/