Thats a false assumption. I'm telling you that hippo is the lowest quality ivory in the world. People use mineral oil baths and every possible concoction trying to prevent loss/splitting as it dries. Not over decades, over days.
Look at any and all of the africa shaped wood plaques that have hippo teeth affixed. You'll note that many of them are split into two pieces and glued or bound back together. Drilling them to a board only makes things worse. Best way to present is pay the extra $$$ to have a brass cap affixed to the tooth base and then affix that brass/nickel cap to a box for presentation so there is less stress on the ivory.
It's all about the hunt anyway, so go for it if you think you'll enjoy the hippo hunt. I'm glad I did it once myself. I'm just making you aware that hunting hippo is A.) a total sh$t show with lots of before and after labor and screwing around whereas you could otherwise be hunting or doing something better with your precios time, B.) The trophy quality of the tusks are very low and you may be devastated to find they are not in good condition when they arrive back home, C.) you could be using the hippo trophy fee to hunt many other species of plains game, and D.) Hippo is one of the most delicious animals in all of Africa to eat.
Lastly, if you told me you were after leopard, hyena, croc or lion I'd tell you to definitely kill the hippo because pound for pound it is the cheapest bait you can buy.
Let us know what you decide!