Why "its" ?

[bieasy]

Hi,

I'm not sure about the accuracy of what I've heard and I had no time to write it down, but I think it was something like: "It's hard to make someone understand something when its salary depends on its not understanding" (An inconvenient truth - Al Gore)
But I'm quite sure he used the pronoun "its" Shouldn't it be "his" instead?

[susiedqq]

I think it was Al Gore's quote: “It is hard to make someone understand something, if his salary depends upon him not understanding it.”

[David L.]

...and he should have said:

“It is hard to make someone understand something, if his salary depends upon his not understanding it.”

[riverkid]

...and he should have said:

“It is hard to make someone understand something, if his salary depends upon his not understanding it.”

Why, David?