It isn't that Lichaa is necessarily better (though I think he is) but that he fills a role we don't have with De Gois out - a solid worker capable of long minutes.
It's obvious Kaysa Pritchard is not an 80 minute hooker. He is a dynamic, explosive player but he is being forced by injuries to average 40 tackles in 70 minutes, similar to slower, hard working hookers like McCullough (55 tackles in 80 minutes), Lichaa (40 tackles in 80), McInnes (45 tackles in 80), Wallace (40 tackles in 80), Friend (45 in 70, though also an explosive player) and Smith (45 in 80).
Ideally a player like Pritchard would be playing fewer minutes, like Granville (60 minutes), Levi (65), Cook (50), Farah (45), Koroisau (65), Brailey (60), Segeyaro (25) and all the nuffies at the Titans and Tigers.
Or he could play long minutes and just bludge in defence like Issac Luke and Josh Hodgson (both making 30 tackles in 70 minutes). But since Pritchard isn't a key player in our attack, just like most hookers aren't, there's no need to hide him in defence. He just needs someone to share his minutes with. I can see the sense in giving the role to Brown, but of course those are wasted minutes where he is getting fatigued in defence without using his strength, which is his running game.