if you usually get points through this channel than it is reasonable to assume this will continue to be the case ... however, if it stops, per HH T&C, you are stuck with it since they explicitely state that no point and stay credit will be given. I agree with the other posters that front desk agents won't necessarily have a clue about this. Also make sure they don't misunderstand your question, because in-hotel benefits will be the same.
You have several stays upcoming? I'd give it a shot and if you get points through this channel while paying a lower rate than on hilton.com make sure you let us know