I think so, unless I'm misinterpreting the concern. According to litecoin's rpcwallet.c, the testnet param will always be returned when getinfo() is called:
https://github.com/litecoin-project/litecoin/blob/master-0.8/src/rpcwallet.cpp#L84

And it's a boolean, so true/false should be the only possible results:
https://github.com/litecoin-project/litecoin/blob/master-0.8/src/util.cpp#L81