Forester 2.5XT (2004-2013) is still listed for DS in the 2017 rule book dated 1/17/17. Perhaps you were looking at a draft version.

Hmmm, so the Jan 17 version only lived two weeks.

The answer to the OP's question is in the February Fastrack:

"#20755 Subaru Forester 2.5XT (2004-13) exceeds rollover concern
Per the SAC, the following car does not meet the rollover guidelines and are ineligable
for competition in the street category. Therefore this listing is to be removed from class
DS:
Subaru
Forester XT (2004-13)"

Time to get yourself some coilovers and a Cobb and run STX!