Ur.. that's probably cos they don't fly to SIN... (It's through HKG...)
Second the idea to try for LX ZRH-BKK... from BKK-SYD... not so sure...
Sudden thought... I recently flew PEK-SYD on CA's new C product (seemed identical to TK's new product to me!) .. Totally flat, very comfortable.. Soft product was'nt great but the seat was!
Don't know what the options are ARN-PEK....