The One Way Question, or the reason I haven't bought my flight to Doha

I was reading the fine print at the end of an Air Arabia flight, and it said, "One way fares exclusive of taxes and surcharges. Standard terms and conditions apply. Not valid for sale from Qatar."

That last bit mystifies me. I can't buy one way fares in Qatar? I can't buy a flight from Qatar? I can't buy from Qatar? The ambiguity of the sentence is too much to bear!

I also am having trouble deciding between my options: January 2nd or January 4th. (I have to be in Doha by the 5th.)

January 2nd:

• Pros: cheaper by $30, less than 2 hour layover, arrive at 9am
• Cons: leave earlier in the week (only spending 3 full days there), leave at 1am on the 2nd

January 4th:

• Pros: another 2 days (spending 5 full days there)
  
• Cons: more expensive, 10 hour layover, leave at 1am but arrive at 6pm

I mean, the really good news is that AirArabia is pretty cheap regardless.

I'm still a bit scared about the one way bit. Does that mean that I'll have to buy a roundtrip ticket to get out of Qatar (when the time comes)?

If you have any suggestions, comment away!