They have to right to do as they see fit. Julian Assange is in Ecudor for asylum and they have the right to do whatever they feel is right as conditions. He is not a free citizen of the United States or any other country and is not covered under freedom of speech.
Yes, Ecuador's response is reasonably proportional and suitable based on the original act of election meddling. Restricting Internet access for Wikileaks is fair under these circumstances. I don't think more extreme measures need to be taken. It's not like lifetime prison terms or anything like that would be warranted. Blocking something temporarily is probably the best solution.
WikiLeak's founder, Julian Assange, has been taking refuge at Ecuador's embassy offices in London since 2012. It is completely understandable that Ecuador is wary of being seen to aid Assange in publishing information on the internet about Clinton that could potentially have an influence on the outcome of the American electoral process.
Yes, this is a proportional response because Assange should not have any influence on the election. His information should only affect the country he is from. Plus, the information he is releasing is classified, and by releasing it, he could cause countries to go to war. Ecuador should remove his internet entirely.