Try a biology or evolutionary biology textbook or research papers if you don't want the truth from experts that posted the last time this question was asked and thoroughly explained.
First: Maybe she did not see the first post. I have seen many questions posted on this site multiple times. This is a legitimate question.
Second: Your everyday layperson and news anchor does not read biology books. Poisonous has been taught to us as small children and it is going to carry over into your adult life.
The term venomous did not come into use until recently. I have seen biology books written by great reptile people in the earlier years of herpetology using the term Poisonous and Poison. I even have a Croc hunter show on tape where he uses the term.
If you want the truth: poisonous is a very acceptable word for a layperson to use.