[Zope] request for security advice

[seb bacon]

I've been trying to log a user in programmatically for a while, and I
think I've finally got it cracked.  All you have to do is create a new
SecurityManager with a user object:

  from AccessControl.SecurityManagement import newSecurityManager
  ...  
  newSecurityManager(None, user)

My question is this: is there any reason why this would be a Bad
Thing, security-wise?

seb