The goal of the code seems unclear. It may have been to have been to prevent the player from having their way way with a slave simply by gaining consent, or simply be an oversight. Sex is messy right now. Currently, obedience is needed to get a slave to willingly participate and consent effects how much the slave enjoys the actions. If you want consent to stop resistance, simply add "person.consent == false && " after the "if" on line 620. But please note that the availability of some actions depends on obedience.
To know what sort of fix would be best, it would help to know how you would like it to work.
Edit: code to insert was wrong, sorry