I just want to make sure I'm not missing something. Typically, I think about Marksmanship when I want to get a crit through. Since the TLT cancels all dice results, you aren't getting that crit. But I can see how getting a focus for both attacks with Horton is great, especially when he's really not going to want to use focus on defense.
I think it costs 3 because of the crit effect. On Horton, though, it seems like a good deal since there isn't really a trade-off with using focus for defense vs. offense. The only concern is that you have to spend the point to give him an Elite slot with the droid. That's 10 points of upgrades on Horton. You better guard him well. Biggs would probably make this build worth it.