In all fairness to the pilot, he may not have seen the cloud until it was too late. If conditions were below SVFR, the viz may have been very poor, and he may not have been able to see the cloud in time to avoid it.
Of course he should never have put himself into that position in the first place.
But it is equally true that ATC should never have instructed him to return to an aiport where the conditions had deteriated so badly. The bit that I don't understand is the fact that ATC instructed him to return BECAUSE the conditions had become so bad!
Why instruct some to turn towards bad weather, because it had gotten so bad?
dp