I created some test sims and abused some cheats and was able to get a sim pregnant via abduction, it just took a while.
Sim 1 was masculine-framed and set to "Becomes pregnant" for his pregnancy options. He showed as pregnant in MCCC after abduction number 2. He showed the morning sickness animation around 12 hours later. He didn't get the tummy ache moodlet until about 48 hours later.
Sim 2 was masculine-framed and set to "Get others pregnant" for his pregnancy options. He showed as pregnant in MCCC after abduction number 7.He showed the morning sickness animation almost a full 17 game hours later. He didn't get the tummy ache moodlet until about 36 hours later.
Sim 3 was masculine-framed and set to "Neither" for his pregnancy options. He died of heat exhaustion after abduction 11 and I felt that was a sign to stop torturing him. May he rest in peace.
Sim 4 was a copy of sim 3 and set to "Get others pregnant" for his pregnancy options.He showed as pregnant in MCCC after abduction number 2.He showed the morning sickness animation almost 4 game hours later. He didn't get the tummy ache moodlet until about 24 hours later.