This is the part that you seem to be confusing.
Apollo and Reddit do not appear to be business partners. Nor does Apollo seem to have any contractual agreement with Reddit, outside of the API usage agreement.
The API terms were lasted updated May 25, 2016. These include this language:
> a. Fees. Reddit reserves the right to charge fees for future use or access to the Reddit APIs, rates to be determined in Reddit’s sole discretion.
I assume these are the terms that Apollo are bound to. If that's the case, I don't see how you can support your claim. Reddit is using it's contractual right.