https://www.nolo.com/legal-encyclopedia/texas-dog-bite-laws.html
If his affirmative defense is contributory negligence -- she was trespassing (therefore she is more than 51% at fault) and the first element of trespassing is INTENT...how does intent not apply here? Of course her intent applies:
She INTENDED to enter Zeke's property (even she is not going to contest that fact). What was she pushed? Drugged? Or intimidated onto the Zeke's property? Of course not. She entered onto Zeke's property and intended (wanted, desired) to do so.
Her motive does not apply as the tort of trespass does not care about her motive (reason).
So the only question left, under Texas law, is was her intentional entry authorized, which Zeke is saying it was not.
If it was not authorized: Zeke has established she was a trespasser, therefore, Zeke owed to her a far less duty (basically to refrain from wanton and willful misconduct). In addition, that she contributed to her own injuries (by trespassing) and under Texas modified comparative negligence statutes she would receive nothing from Zeke.
Not sure why you are mentioning principal-agent relationship here unless you are saying that she should go sue her employer because her injuries were sustained in the course and scope of her employment. And in that case, she should be suing her employer...not Zeke.