According to the dossiers, the reason why the titanosaur doesn’t eat is because it prefers to die rather than being held in captivity forever. And for single player, it eats because it is glad to serve a a master which is one of a kind (you are the only human because it’s single player). These are great for single player, despite the fact that you can’t level it stats, only torpor, but it’s stats are already OP, so I guess it’s plausible.

How to kill a titan that is near water:

Items needed:

A good lvl mosa with a saddle

A high dmg ranged weapon (gun, crossbow etc.)

Ammo for the weapon

Method:

Lure the titan into the water with the weapon

Attack the tail of the titan with the mosa - this will mean that it will not be able to hit you in the water

Once titan gets to a few thousand hp left, shoot with the weapon until it dies.

Celebrate your success by upping

I got level 95 very fast by killing Titanosaurs. The best way is to use a lightning Wyvern and fire it from above, watch your stamina. You can also use a very good Giga (good melee and good saddle is a must) to kill it fast, try to hide behind a Redwood tree, take your time and watch your stamina. If anything goes wrong (Giga stuck in a tree) dismount from it and shoot arrows at the Titan, it will start chasing you, hide behind a tree and wait. The titan will become passive. Good hunt and don't forget the broth for exp x2 ! :)

If you really want to kill one of these things, just life it out to water. MAKE SURE IT IS FULLY SUBMERGED OTHERWISE IT CAN STILL KILL YOU. If you have scuba gear and a good sword, it really helps. Then, because it can’t attack underwater, just keep swiping it with your sword. Bam. Easy xp