Yes. He would've too if his "little secret" revealed didn't give Simba such an adrenalin rush.

And even at Simba's cubhood I believe Scar could've. He simply did not want to because at the first point it would've been too obviously pointing to him, and after the second fail he needed to reward the three hyenas if he wished to keep them loyal to him. Hence, let them kill the cub.

As in real life since Scar is not Simba's father and Mufasa was killed Scar would of killed him himself as a male lion that takes over a pride would kill the existing cubs.

I agree with bendaimmortal and boytoy_84.