Torture is available before the Ban option. It also occurs before the infiltrator will get their own escape option (though they can still get the random game generated auto escape. Torture has long been used to stop a infil from logging in right on TC to escape before a ban can be read. And since torture doesn't release the infiltrator, you can still ban or execute them without needing to recapture them.
The other important piece of info is that good infils are hard to execute. You only have to look at how many times Hailey has managed to escape that result. When you choose to execute the infil the game generates one more chance to escape, and from all appearances if the infiltrator is very skill, it is a reasonable chance. In fact that is why some realms elect to simply deport them (there are other reasons, like being nice or prisoner treaties) It is simply a more reliable way to reduce infiltrator attacks, even if it does only work for a dew weeks.
