manta.com inbound link directory

[David]

I've been working on SEO for local small business in Frederick Maryland.
Some companies, especially construction companies that do NOT have websites are listed by a third party directory.

From what I can tell, these construction companies:

• Do not think they need a website
• Get the bulk of their contracts from government bids
• Are 'old school' good ole boy network types
• Probably dont even have a computer let alone know how to work one

These companies can be found in google however... under this website:
Company Profiles & Company Information on Manta

I'm wondering... I do see a place where if you own a company listed there
(manta.com seems to use verizon public phone book listings for 'data')
(manta.com apparently lists companies without the companies knowledge)

would it be beneficial to go ahead and claim a listing... OR
is there something fishy about manta.com listing a company without the companies participation/ knowledge/ authorization ???

would claiming a listing help or hurt in terms of SEO for a company???
thanks