In neither answer was the matter of how the individual obtained information on someone else's pay addressed.   This is significant as there may be a privacy violation. It is certainly appropriate for an employee to inquire about his or her pay, but it is absolutely inappropriate to reference the pay of a specific individual unless this information is in the public domain.    Further, length of experience is only one consideration in determining salary.  What about education and performance?  Two people can do the same job and one just happens to perform better.  With respect to market research around pay, companies typically do this and measure themselves against an appropriate peer group of comparable organizations.  Often this is conducted through a third party.  Certainly, an individual can do some checking but the data is only as reliable as the source.  
G & M, it would probably be a good idea to vet information provided in the answers in this column sometimes.