What does "强横" mean when it is used to describe an inanimate things?
zdic says 强横: 骄横跋扈;强硬蛮横。亦指这样的人.  

亦指这样的人 is not very clear. I suspect what it means is that in addition to functioning as a modifier (brutal and unreasonable), 强横 can also function as a nominal by itself (a brutal and unreasonable person). It doesn't give an example of this, however.

强横 refers to a type of person, or perhaps actions or policies that people implement.  I don't think it could refer to something inanimate, or even an animal. 

zdic glosses 横 as 'unreasonable'. 横 refers to someone who goes straight ahead without following a road or path (reason or morality).

I also don't think 强 really means strong here; it is more like the 强 in 強盜 'robber'.  The MOE 國語辭典 defines this sense of 强 as 橫暴.

In any case, 强横 is never going to be neutral, just like 霸道 or 講理 are not neutral. Someone who is 强横 is a bad guy.