There must have been a reason. Amtrak isnt an idiot, they probably had a slight idea with what they wanted to do.
Alec
The GP40TC's have a pretty interesting history. They were originally owned by GO Transit and spent close to 20 years in Toronto suburban service. They were sold to Amtrak who based them out of Chicago for short-haul trains, although they seem to have turned up pretty regularly on the Capitol Ltd. After the various Genesis units went into service, they were rebuilt at Juniata into GP38H-3's in 2004-2005 for switching and M/W service. See this link for more information http://www.gobytrain.us/amtrak/notes/index.html#GP40PH