As a grandmaster of his generation, Master Roshi not only possessed profound martial arts attainments, but also placed great importance on his disciples' moral education.
He knew well that if his disciples won too easily in the tournament, or were only defeated by He-El, whom they had always considered merely stronger than themselves, then even in defeat, they might still become arrogant when facing others. They might even take extreme or evil paths in their desire to defeat He-El.
Therefore, Master Roshi wanted to conceal his identity and personally enter the World Martial Arts Tournament, using his own actions to demonstrate how victory and defeat should be properly faced.
By directly confronting his disciples, he hoped they would learn the importance of humility and diligence.
This was also an important lesson Master Roshi wanted to teach Goku and Krillin.
However, when he learned that He-El would also be entering the World Martial Arts Tournament, Master Roshi became somewhat hesitant about whether he should participate.
Having He-El defeat Goku seemed pretty good too.
But Goku and He-El had known each other for a long time, so it would not achieve the desired educational effect on Goku.
Thus, Master Roshi wanted to discuss it with He-El beforehand.
"This is very good. It will let Goku and Krillin know that they are not the strongest in this world, and neither am I. There will always be someone greater beyond the horizon, someone stronger beyond the strong. I support you in doing this."
He-El nodded seriously, fully supporting Master Roshi's education of Goku.
The pursuit of strength and the thrill of battle were traits Saiyans could never change. Vegito was a clear example of that.
All the dead Saiyans were examples of the same thing.
Otherwise, they would not have been called the warrior