The old characters weren't bundled in a season pass simply because in the past this marketing strategy wasn't used. While it's right that this can help to improve the sellings of a character not popular forced to be bought only separately, I believe that this alone doesn't say anything about it being more likely a male character.
This was my same previous reasoning for thinking that this new character was more likely to be a male one (or a not conventional female, as for example an old lady), but I've always also considered that they could add new DLC characters with remakes of DoAX3 after to have realized the commercial success of the original title, exactly as happened with the DoA5 series where remains true that no DLC characters were added to the vanilla version.
The inclusion of a debut set doesn't give a confirmation about the gender of the character, but definitely gives an high chance to it being female considering that Raidou didn't receive a debut set. Of course could happen even other scenarios, for example a male character with only 3 costumes and a debut set for increasing it, but considering the past experience they remain unlikely because without previous examples.