The benefit of bring irregulars cannot be gotten from tagging along with one. The 10GW came into the tower with other people, none of which are recognized as irregulars, but Siu confirmed that Rachel is an irregular in a tweet
To be honest, this has never been confirmed.
It is not confirmed that other people have entered with the 13GW, it is just an assumption, it is not for nothing that many considered the idea of Illarde being a clone of Hana.
Second, if it is confirmed that others have entered as well, there is nothing to say that they are not irregulars, SIU said that the number of irregulars is unknown.
It's okay for Rachel to be irregular, but if Baam is the one who opened the door for her, she's not genuinely one. She can escape the guides' vision, but she is unable to change fate.