I think it is still better than leaving the aircraft on the tarmac. From the article, THAI selects OSL due to the followings:
1. less or no direct competitor on this route
2. THAI has 6 active staff there at Oslo office
3. Bring in some revenues and they don't expect a lot of profits
4. Better than just park those 4 aircraft
5. Fuel cost is cheaper
6. No landing fee for 1 year
7. Many Norwegians love to visit Thailand