This has been the plan all along. However, the way they need to do this to avoid a tax burden on SIAF is different than what they planned in the past.
There is a speculation that TRW might convert more of its debt and that SIAF will retain its 36.6% even post the 18.3%-distribution, but SIAF has been saying that they plan on distributing half of their 36.6% stake ever since they acquired that stake. The speculation isn't totally unreasonable (especially if SIAF/TRW isn't able to reverse the 36.6% in such a way that SIAF is unable to avoid the tax burden of the 36.6% they already have), but we don't have any indications so far except for a strange wording in the TRW-announcement.