See the nrc article here which outlines that the trade unions denounce the policies of board and management of ABN AMRO. This vision is identical to that of the association of shareholders (VEB) and just as the VEB the trade unions request an investigation into the board and management policy and governance at ABN AMRO. Their argument is that by selling of LaSalle, the board didn't properly take into account that the RBS-constortium does give an employement guarantee, while Barclays does explicitly not give such a guarantee.
By requesting the enterprise court to hold an investigation into the ABN AMRO policies, VEB and trade unions have used on of the few approaches available that will allow the Enterprise Court to uphold its previous verdict in the LaSalle case (obligation not to sell) yet on different grounds (bad governance). So it's look as if its going to be a long hot summer after all...