It isn't good to starve a growing fish. Bad advice. A 7" aro going weeks without food is ridiculous. They're still sensitive till about a foot.
Temperature size and genetics dictate metabolism, but 2 weeks with out food with a 6-7" arowana probably isn't a good regular feeding schedule, but shouldn't kill an other wise healthy arowana. It may actually refuse food for that period after a move any way.
But a 6" arowana is by no means out grown a 150g either.
An arowana could live at and stay close to 1' for over a year in that setup. I wouldn't use 2 weeks as a normal feeding schedule, but I've had silver go a few weeks at that size with out harm. Though personally I feed mine every other day.
Last house move I was on a once a week to once every other week that I was home and able to feed my fish over a 4 month period while I was renovating new house and setting up new tank, didn't lose any fish. Though the smallest arowana I had then was closer to 8" at the start, and grew maybe 1-2" with that feeding schedule over 4 months, had temperature at 72f. After moving I slowly raised temp up to 83f, and increased feedings with temperature, in the first month at 83 had the same 1-2" growth that I had in the 4 months prior.
I personally wouldn't but you could keep it in the 150g for 18 months-life, don't see it being a problem, long as your parameters are stable and you have a good lid. Keep temps down and growth will slow. Fish live longer, grow slower and have lower aggression at lower temps (based on range for species).
Down side to lower temp is disease also lives longer, grows slower. So an outbreak takes longer to fix, nitrification/de-nitrification(assuming you have this) takes larger quantities of bacteria for the same mass at lower temps.
