While I can think of a dozen nefarious reasons for a MSC to ask you for this information, I cannot think of a single reason which would be considered reasonable or appropriate.
If a MSC is interested in how their "customer service" stacks up to others it can be done via a simple survey of their shoppers using language such as, "Compared to other companies you work with are we: A. more accessible, B. less accessible, C. About the same." I have actually seen surveys of this nature and at no time did they ask for the names of other companies.
OTOH, if the MSC is trying to gather intel on their competitors with an eye toward acquiring the company or poaching their clients there are a variety of methods available to them. An employee could check out company websites for industries served and job boards for fee information.
History shows that those who have been quite willing to break a confidence for monetary gain also have found the recipients of the information quite willing to reciprocate by severing all ties with the turncoat. And just how much is 30 pieces of silver in 2014 dollars? Seems like it should be a lot more than $50.
Equal rights for others does not mean fewer rights for you. It's not pie.
"I prefer someone who burns the flag and then wraps themselves up in the Constitution over someone who burns the Constitution and then wraps themselves up in the flag." -Molly Ivins
Never try to teach a pig to sing. It's a waste of your time and it really annoys the pig.