This story has many interesting questions that become apparent upon investigation. This means that Achar perhaps would not have had any special reward in the next world, but he certainly would not have received a punishment. Certainly a person who is raise as a righteous person and studies the ways of righteousness and who raises many students who are proficient and able righteous persons should continue in his chosen path. Yet the answer is simple and shocking. Achar was a Torah scholar par excellence.
Pleasure comes on many levels.
The lowest level in the pure animalistic or bodily pleasures such as eating and drinking etc. This is a easily attained pleasure, but very short lived. Then there is the emotional level of pleasure, when we reach a plateau such as marriage, a child is born. This pleasure is longer lasting then the first, and lasts longer, but more difficult to attain. Then there is the mental level of pleasure.