Does this sound reasonable?
Yes! In this instance, with the benefit of local knowledge, they were probably departing off YBAS 30. I don't fly RNPs but, if their RNP did an immediate left turn to the south (no hills on that path), that they would have had XXXXXkg RTOW.
Now if ATC had said "maintain runway heading", straight towards the large mountain (ok hill) range on the extended centreline, their RTOW (they would have had to have used a different RTOW chart or different departure in their EFB) would have been less. Some departures may be so different, obstacle-wise, that you need to use a different chart/EFB input to arrive at the RTOW.