Swera, here is another link from a website, similar to that you posted the link from.
Title:
Attending Funerals of Non-Muslims
Question:
What is the position of attending funerals of non-Muslims?
Answer:
While living in a mixed society, one generally has social relations with people ascribing to other faiths as well. Good and healthy social relations with others, besides being a part of man’s social nature, also provide the very foundation and basis of propagating Islam to others. Obviously, if we do not have a healthy social interaction with others, there is hardly a chance that we shall be able to attract them to the message of Islam. Thus, healthy social interaction with others (irrespective of their religious beliefs and ascriptions), in my opinion, is not only in consonance with man’s social nature but also a requirement for any subsequent opportunity of propagating the views that we hold to be true.
Congratulating and offering our good wishes to others in times of happiness and standing by their side and offering our condolences in times of sadness are two major periods of social interaction. Death of a friend or a friend’s loved one, irrespective of his/her religious affiliations, is a time when that friend (or his/her family) needs us by his/her side the most. We should consider ourselves extremely lucky, if our presence, at such times, can be source of comforting another human being.
In my opinion, therefore, **as it has not been explicitly prohibited by the Shari`ah, it should not only be considered allowed to attend a funeral of a non-Muslim friend or relative **or his/her loved one, but should also be looked upon as an opportunity to show our love, affection and strong social ties with that friend and his family.
These are, in fact, times and opportunities to be human. And Islam, I assure you, endorses all that is human.
www.understandingislam.com
So clealy there are divisions among these scholars, had there been an explicit refusal, yes we have to follow that but there is not, so do what you think is humane.