I would not be surprised if it is true - what you have to understand is that there is an accepted belief that LE commissionees are seen broadly as polyfilla for the benefit of the Regiments/Corps.
That said there are a few jobs that cannot be filled by DEs and need experienced personnel however if you were asked to do a family officers job after being a hands on gunnery god or similar would you give it a second thought?
In addition a WO1 based in Germany is on higher LOA than his CO and if he were to get posted to UK as a Captain he would be much worse off - wheres the incentive in that? More responsibility less money mmmm not hard to make a decision on that one.
The pension is another question however he has to be converted and make major to benefit from the real pension gains. As a rule of thumb a Min of 6 years. If hes a young WO1 say 36, picks up his majority at 42 he faces 10 years at that rank before hes even considered for a look at half colonel - very much right place right time.
They may also be thinking why become shit of the kings when I can stay King of the Shits and in some cases till 55.
There is of course the prestige that comes with a commission and it involves a lifestyle change too not only for the individual but the wife too. This may factor heavily in the decision to commission also.
Bottom line is its not for everyone so if your in the bracket give it some thought - dont jump at it because you see it as a natural progression/promotion - its actually an entire change of career.