Here's his response:(Note that the "to each constant" part seems to suggest that Lojban doesn't allow the use of function symbols as a part of its syntax. It might be so or the writer just forgot their existence. Whether they are allowed or not makes a great difference on the theoretical capabilities of the language but, again, they are mostly not relevant to what I'm going to post about so I'll mostly ignore them, too).
The reason why this is not a problem for Lojban speakers is that they aren't actually doing any first-order reasoning with it. They are using it in exactly the same way as they would use an ordinary language, together with all the fuzziness and imprecision of such languages. Lojban in reality is a completely ordinary language with a slightly unusual grammar.