If you read your own link, it says benefits for the families of terrorists - there is a difference.
If someone goes to prison for drink driving, should his wife and children be denied benefits? They are innocent.
If someone goes to prison for fraud, should his wife and children be denied any benefit? They are innocent.
Likewise if a man is convicted of a terrorist charge, the wife and children have done nothing, they are innocent, and should be treated the same as everyone else.
This yet again illustrates how ridiculous is the concept of a "european court" in its relevance to this country. Why some appointed foreign lawyers of unknown provenance should have any influence in the way in which the courts of the United Kingdom administer justice within the United Kingdom beggars belief.
One of the reasons criminals commit crimes is that they know their families will be well looked after. In fact without a "bread winner " the family qualify for all the extra benefits.
As long as a terrorist is under the judgement of the court the family can stay in this country at our expense even over many years, which in reality is for ever.