No they know the useragent string, but their site is not capable of rendering for old browsers. Mozilla4 is really old, so they throw an error page
.
I will submit a patch to synapse to change the useragent string to something that is 10 years old rather than 20.. Usually these are still applied.
Actually this is useragent spoofing, since no browser is used. See the link to wikipedia.
Anyway, this way you can obtain a fully rendered page.