It should be considered travel. I know I've used the purchase eraser for
DCL ground transfers and it counted as travel. What I find most annoying about the PE is that you must have enough points in your account to cover any particular charge completely. You can't just apply the points you have toward a higher amount of travel and pay for the remaining amount.
I had around $40 worth of CO points and had hoped to apply to our onboard account for a Med cruise 2 years ago. I couldn't do that because all of the charges were greater than $40 except for a charge of $16 for cab fare in Barcelona.

Lesson learned.
So the last time I wanted to apply an odd number of points toward the cost of our DCL ground transfers, I asked my TA to enter is as 2 separate charges: one that equaled the amount of points I could use to erase it, and then the rest. Good thing we've been using her for years and she was so nice about it but once those points were gone, I was done with that travel eraser. 99.99% of our travel is domestic so the SWA card gives us great perks. Everyone has different needs so I imagine the CO card works for many people, just not for me. I still have it for rare times when we might need to avoid an international use fee but it's not my regular card.
Sorry to go off on a rant a little there. I just wished someone had explained that to me before I assumed I could apply partial amount of points toward the bill.