In this specific context the dot won't do any harm, but it isn't needed... UNLESS there exist sites called, say, exampleofgoodstuff.com and you don't want to block those. Then it can make a big difference.
SetEnvIf and the shortcut BrowserMatch both use Regular Expressions. That means an unescaped dot . means "any character at all". If you need it to mean "only a dot and nothing else" then you have to escape it with a backslash like this \.