Of course they should have that freedom to plead for themselves, and it seems to me they still have it. The trouble begins when a part in the case tries decisively, more or less openly, to guide the work of the police, make them go in one direction and keep out of other areas. There has to be a clear boundary between publicity/interviews and journalism on one hand and the police work on the other, and because the news is getting very upfront with persons - everything is personalized - some interviews and scoops really spell a kind of campaign writing, attempts to wrestle for control over what the police are doing.
Most of what's been written about this in the UK, at least before the couple were named as aguidos and returned home, has been following the view that Madeline's been abducted and has been very favourable to the parents, isn't that true? Outside of the UK and Portugal, I think almost all coverage up to that moment was from their point of view, and much of what's been around in newspapers in Sweden is simple rewrite of The Sun and News Of the World, two papers that are not known for doing careful and unbiased research into a story.