Is .NET impersonation logon thread-safe?

If using code like the following to impersonate another user,

[DllImport("advapi32.dll", SetLastError = true)]

private static extern bool

LogonUser(string lpszUsername, string lpszDomain,
          string lpszPassword, int dwLogonType,
          int dwLogonProvider, ref IntPtr phToken);
var handle = IntPtr.Zero;

const int LOGON32_LOGON_NETWORK = 3;
const int LOGON32_PROVIDER_DEFAULT = 0;
const int SecurityImpersonation = 2;
LogonUser(username, domain,
          password, LOGON32_LOGON_NETWORK,
          LOGON32_PROVIDER_DEFAULT, ref handle))

on two different concurrent threads, will they interfere with one another? I.e., is the currently logged-on user associated with the thread, or with the host process?

I am using the logon handle to create a WindowsImpersonationContext object, as a private state field in an instance of a type I named "Impersonator" (code below). So, since this WindowsImpersonationContext object is a local private field in an instance of this type, and a new instance of this type is created each time I want to impersonate some set of credentials, I can assume that this WindowsImpersonationContext is what is being used to perform all ACL validations during execution of code within a block such as

   using (Impersonator.Impersonate(userId, domain, password))
   {
       // Code I want to execute using supplied credentials
   }

What has me concerned is the statement on the MSDN page WindowsImpersonationContext that says:

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Impersonator class:

public class Impersonator: IDisposable
{
    #region Declarations
        private