Which still leaves that potential case being in the minority of use, which is what I was pointing out. $iscmd or whatever would be much more widely used and would be more of a requirement.
It is highly unlikely that the command character setting in mirc.ini will ever change as it's used by so many scripts. Khaled would be crazy to change that. So there isn't a requirement for a "safe" way to get it. As I said, it would make sense to add both, but the $iscmd would be much more important and is what the OP was really asking for anyhow.