This should work, it also allows the word following the command to be optional if that's what you want.This format only allows 0 or 1 words following the !command. If what you want changes, so will the pattern.
on $^*:TEXT:/^(\.|!)(c|command)( +[^ ]+$|$)/i:#:{
echo -g # $chr(22) $scriptline debug: ($1-) $1- regml1: $qt($regml(1)) regml2: $qt($regml(2)) | halt
}