content-type is used by browsers to find out how the content is displayed. Browsers must choose the presentation method based on the content type. Rendering simple text is very different from rendering HTML.
wget Performs the same action on all files: they are stored on the hard disk. In my experience, it does not pay attention to the
Content-Type Header, it only saves the file. Most file systems have no other mechanism to store metadata about the file than the file name and permissions. The content type is not even saved.
The only exception could be Mac OS. Mac's file systems can store far more metadata about files than other file system references. I have never used
wget on the Mac, but it is possible that the content type will be saved there as a file metadata. This would then affect which program opens the file with the default action.
Of course, other file systems will usually guess based on the file extension
.html, Since this is also wrong, the systems may behave the same way as the application types selected to open the saved file.
If you use the UUID with a specific script or application, it probably does not matter to you what the operating system would choose as the default editor and viewer for the file. I can not imagine that your use case on Windows, Mac or Linux will cause unforeseen problems.