Just because you opt out of letting Facebook (or Linkedin) see your contacts, does not mean your contacts have done the same thing.
e.g. If you are [email protected], and others have [email protected] in their address book and they let Facebook see it, they've got you already.
For this reason I use a dedicated email address for each social media account.
Also, while I'd normally recommend 2-factor authentication, giving these guys your phone number is a really bad idea if you value your privacy. Try to limit it to firstname lastname and one throwaway email if at all possible. If you're really paranoid, you can get a VOIP gateway that supports SMS for fairly cheap, certainly for cheaper than buying a burner phone.
e.g. If you are [email protected], and others have [email protected] in their address book and they let Facebook see it, they've got you already.
For this reason I use a dedicated email address for each social media account.
Also, while I'd normally recommend 2-factor authentication, giving these guys your phone number is a really bad idea if you value your privacy. Try to limit it to firstname lastname and one throwaway email if at all possible. If you're really paranoid, you can get a VOIP gateway that supports SMS for fairly cheap, certainly for cheaper than buying a burner phone.