The spec, design and code surrounding the website won't be considered in marking for a degree in computer science. The underlying algorithm designs, scientific methodology, data analysis, results, presentation of findings, novelty of solution, literature review will all be considered as the basis of the grade.
The spec, design and code will be considered insomuch as they form the basis for the results, analysis and presentation of findings; I didn't say that the project mark would be based on a code review. (Though a commercially driven project, which some institutions allow, may still involve one I suppose.)
I'm not saying that a CS project can simply consist of code and a quick "I did this" write up; of course the project needs to be fully documented from inception through to presentation, including sufficient commentary on each aspect to show (for lack of a better way to put this) that you know what the hell you're talking about. Of course there needs to be a question that you are trying to answer with your project. All I am saying is that you don't have to create a piece of pure scientific research; software development can be a project in its own right.
[ EDIT: And there's usually the "original work" requirement, of course, which generally means that you can't just take a previous student's title that you like the sound of and say "yeah, I'll have a crack at that too", unless you plan to expand on or further the work. Original work doesn't quite mean the same thing with software development though - your concepts don't have to be new, if the project itself is somehow an original take on them. ]
Different institutions and supervisors will vary of course, which I'm sure is the source of this disagreement, but what I've described is most certainly acceptable at some top 10 universities in the UK.
As always, students, speak to your supervisor. They will know the specific requirements your university imposes for a final year project, and can advise.
[ EDIT2: I'm not commenting on the suitability of the OP's suggested project, by the way. That's a matter for the OP to discuss with his or her supervisor at their earliest convenience. ]