I'm currently using TiTs version 6.7. I think that since the Zil are the only ones who drop the primitive bows so far, it would make sense that Burt would be interested in them as collectibles. I'm not saying that they should be worth a fortune, just that he should be interested in them. It seems to fit with the lore a bit better than having him say that "This has nothing to do with the Zil."