You’re probably right. Their goal was twofold: 1. get incumbents renominated and ride a republican tide to reelection, and 2. prevent conservatives from being nominated, thus only moderate or go-along types would be swept into the Senate by such a tide.
They also wanted to 3. destroy the prospect of primary challenges and dry up the Senate Conservatives Fund and other groups’ power in provoking such primary challenges. In this last, they failed. Their incumbents won by the skin of their teeth in some races and pitifully so in others, and all with overwhelming money and chicanery, which won’t last.