Unfortunately “bigger times are better” setting is only applicable to categories, and this setting is necessary for a score based leaderboard to reflect the placements correctly

Technically there are score-based leaderboards on speedrun.com such as Metal Gear Solid 2 VR missions (https://www.speedrun.com/mgs2vr/levels) where the “times” are sorted from the biggest to the smallest. However, this wouldn’t work for MW12, since only a part of ILs in it are score based, and the “longer times are better” setting only is applicable to an entire category with how the IL boards are structured. So it’s not possible unless one’s willing to create a score based category and put in a bunch of N/A runs into the time-based ILs in the category and vice versa, which is a crutch solution at best.

It's a part of Bioshock: The Collection leaderboard: https://www.speedrun.com/bstc?h=BioShock_2-Any-PC&x=xd1m53zd-wl3q1yn1.81w4o99q-ylq9k278.klrj90oq