"From a lot of respects it's not surprising, we are quite used to these issues coming up, but it is surprising that quite a well-known New Zealander would take it up for that purpose and I think that's really disappointing."
The DPA is national organisation that works at a high policy level to ensure that the rights of disabled people are met.
She said while DPA was of the view that the toilets could be used by anyone, especially at airports, there needed to be some respect shown for their use as there weren't many around.
"For some people those are the only toilets that they can use and there's not many of them, there's normally only one, so if that toilet is taken up for 10 minutes it means that a disabled person coming in isn't able to use any of the other stalls and so is really caught short in a lot of senses."
Christchurch Airport has also condemned the "inappropriate" behaviour by the rugby player in the terminal's toilets.
"Like many public facilities, we have disabled facilities.
"We don't condone inappropriate behaviour at our airport and we understand that matters are being dealt with between the All Blacks and the player concerned," a spokeswoman said.
Smith is now heading back to New Zealand from South Africa and will miss Sunday's test in Durban. New Zealand Rugby confirmed Smith will face a misconduct hearing on his return to New Zealand.
The incident occurred after the All Blacks' 41-13 victory in Christchurch on September 17. All Blacks management were only made aware of the incident this week once they arrived in South Africa for their final Rugby Championship test.