This is how it starts. People discussing potential lesbian horses and before you know it we have another shitty article about “bronies upset over blah blah blah” from the DailyDot.
It’s not canon. It was left very vague, so if people want to believe they are still friends, you damn well can’t prove them wrong.
But the interaction in this episode can definitely be interpreted as shipping fuel if you want. Then again, almost any positive interaction between characters could potentially be interpreted as shipping fuel.
Either way, non-shippers will hold that they are friends (perfectly reasonable), and shippers will continue to see them as being in a relationship. Maybe with the whole “best friends” thing, some shippers will switch to headcanoning that they get into a relationship at a later date or something.
Either way, their interaction in this episode was friendshipping, but it was pretty good shipping fuel too. Hopefully shippers and non-shippers will be satisfied.