Thai Airways staff in Stockholm just asked for my onward ticket when I checked my luggage. They were happy with my bus ticket to Penang, which was less than 30 days out. Just sharing FYI.
TLDR : Answer Summary
A traveler shared their experience at Stockholm airport with Thai Airways, where they were asked about an onward ticket when checking luggage. The airline accepted their bus ticket to Penang, which was valid for less than 30 days after arrival.