Is Spain's constitution set up such that their president can issue a pardon in such cases? That would be the easy political way out for them. The stupid court is encouraged to try them in absentia then their president issues a pardon.
Of course there will be a pardon since the political damage would be really immense to Spain if those GIs would be arrested. This idiotic court desicion is not even in the interest of the socialist gouvernment of Spain. Zapatero knows that very well.