I got a good deal on a Motobecane Nemesis but I'm not really a trithlete, so I was thinking of swapping out the bars and shifters for regular drop bars and STI shifters. Does this sound like a dumb idea? Has anyone else done it? Thanks for your advice.

Sure it is doable, I had mine setup this way for a year and used it to commute.

The only real issue is the combination of a short head tube (low bar height) and steep seat tube meant that I couldn't get the seat back far enough to take weight off my hands. It was fine for my commute (~40 min) but anything over an hour was hard on the shoulders and triceps. I used a 35mm offset seat post and slammed the seat all the way back and it still wasn't enough.

I have never done it but looking at the geometry of the nemesis I would say you wont have a problem. Although just know that decent brifters will run you 2 or 3 hundred dollars. Stems and road bars are cheap. U can get good bars for 20 or 30 bucks.

As far as the fit goes, I like to ride real low and I like tri geometry. You can also get a thomson setback post which will allow you to get more distance between the bars and the saddle.

And I think the Nemesis shares the same geometry as the motobecane Track pro. It looks like the frames come out of the same mold accept the nemesis has all the attached cable routers, etc. So money aside I dont think you will have a problem.

You might be able to mount your current shifters as barcons so all you need is a new stem, bar, and some traditional brake levers. These might also be an option https://retroshift.com/