An interesting point indeed. Something that needs answering.
There is a poster who's in the know, but hasn't provided anything to prove they know anything. I'm sure they'll be along shortly.
I'm not in the know re SISU's investments but I do know about finance.
1. The club is trying to operate as a self-financing unit, I imagine including some interest payments and dividends to the SISU fund that bought CCFC. Hence any income from sales (Wilson, Maddison) could well be paid immediately to SISU to cover debt and equity payments as they will be desperate to show a return from their dismal investment.
2. The club might well be in a different fund to their other investments in oil. Hence there could be no direct link between the two. However they may also be in the same fund too. If they wanted to invest more money to build a stadium they would have to persuade the investors in the relevant fund to stump up more cash. If they were the same investors that have taken the hit on oil they may be reluctant to spend more at this stage. Not that I believe that they will anyway as there is not the return or compelling business case to them that getting the Ricoh for a song would have offered.
I think that we were unlikely to get any further investments or keep any transfer income anyway - so the net result of poor performance in another sector would probably make no difference. I do wonder how SISU is surviving with such a terrible investment record - so what it could do is expedite their demise.