No one is claiming Clinton or Obama broke the law… neither is Trump breaking the law by setting up his organization. The thread is about to what extent ex President interfere with the existing administration. Clinton and Obama did, you need only look at their comments regarding the existing administration… Clinton and Obama have not limited themselves to only philanthropic pursuits.
With regard to the Clinton foundation, nothing illustrates how much the Foundation was involved in politics than the drop in donations as soon as Hillary lost in 2016.
It is likely Trump will do the same thing… Traditionally, Presidents avoided any criticism of the present administration… nothing prevents them from doing so… but was considered both a courtesy and important not to do so.