Explanation

It’s easiest to start this sentence with the second blank, where record labels are described as demanding indefensibly large percentages of [artists’] profits. This means the second blank should be swindle.

The third blank then uses the word equally, implying that downloading a song illegally is also a kind of swindle. Both justifiable and scrupulous are positive words, so you need unconscionable, meaning “not right or reasonable.”

Now you can return to the first blank. You know that the prompt as a whole argues that downloading music is bad, so “in order to defend” it, one must be slightly dishonest. Probity and leniency are both good things. You want contortion, meaning “twisting or bending out of something’s normal shape.”

Contortion, swindle, unconscionable.