Is "Do such-and-such, and you are divorced" considered a conditional divorce, and is it permissible to adopt the view of Ibn Taymiyyah regarding it if the intention is to encourage, prevent, or threaten?

This is a conditional divorce (talaq (definition) mu'allaq), and a Muslim acts, concerning matters disagreed upon by scholars, according to what they believe is most likely correct. This is either by examining the evidence and acting upon the strongest opinion if capable, or by following the most trustworthy scholar if not qualified to examine the evidence. So, if the correctness of Ibn Taymiyyah's opinion (may Allah have mercy on him) in this matter becomes clear to you, there is no harm in acting upon it.