My thoughts on why the algorithm is secret :

   The chip is (regretably) likely to become a standard.   There will
   be many applications where economic factors dictate use of this
   chip, like it or not.

   If the alrogithm is public, and the code is as secure (absent the 
   access to escrowed keys) as represented, an enterprising sort 
   would make "compatible crypto chips for which no key had been
   escrowed".  This is likely what the release was refering to when 
   they refered to the secrecy of the algorithm protecting the
   security of the escrow system.