This is the correct answer. When making a concession like this, always take something away. "We can do the website in 6 weeks, but we will have to remove the ab

This is the correct answer. When making a concession like this, always take something away. "We can do the website in 6 weeks, but we will have to remove the ability for users to upvote". If that doesn't sit well, send a list of the features, along with their timeframes and ask them to choose which features to cut. You still get the irrational answers back though unfortunately, but it is a more balanced position.