Fixing this bug, which is a small tweak anyway, would require cluttering memory with upwards of 20 new plugins. In my opinion, it's not worth it, and no one has really complained about this issue. It's more of a vBulletin bug anyway, since the checkbox selection is not persistent - again, among the post options they do, they don't store this one value.
If we want this fixed, the vBulletin bug should be fixed first. Patching it ourselves is clumsy and uses extra resources. Once the value exists in the database, it's quite easy just to add a check for it before parsing the autolinks.