I am not sure if that article talks about SIA as the airline or SIA as the whole group. SIA's engineering and maintenance is a whole different company, I think it's called SIAEC...not too sure of the name.
So, maybe, SIA has offloaded most of their maintenance cost to SIAEC and doesn't really reflect the true amount in their book keeping.
It's easy for journalists to make sensational allegations and comparisons to stoke emotions. But in auditing, I think there are a lot of other stuff involved.
Just the fact that the journalist, or rather a blogger, just took income and converted it to MYR shows his reporting as too simplistic.
Actually, just based on the table posted on that article, most of the expenses in percentage seems almost identical between SIA and MAS, except for maintenance. Also, maybe, just maybe, MAS' aircraft are much older and therefore needs more maintenance. Maintaining those 30 odd B734 must be a huge cost for MAS.
I'm not accountant, so I take it all with a pinch of salt. I've read other successful airlines' financial reports and there seems more in their report as opposed to the article.