I think the goal in doing this isn't so much as a dividend, but to reduce the discount between the and the B shares. I imagine Grifols management is getting some heat from US holders who have seen their share prices drop dramatically since the buyout. Grifols had put in place preferential dividend treatment on the B's to try and avoid this, but this has not worked. Getting the B's trading in Spain will hopefully help address this.
Regardless, the stock is still cheap and should do well in the long run.
Grifols is known for being shareholder friendly, so I think they will continue to do things to address this gap.