The question "why" has two interpretations in this context. You could be asking what circumstances have been chosen that may affect the strike price of this warrant or you may be asking why the company chose to write a warrant with a modifiable strike price, instead of a more standard warrant. I will answer the latter since you can look up the former in the offering document.
Since a warrant is issued by the company itself, normally as a part of a compensation or incentive package, it need not be as standardized as an option would be. It is a general contract between the company and the recipient and may include all kinds of strange clauses.
Why would the company do this? Remember, the objective of the warrant writer is generally not to make money on the warrant itself, as it would be for an option writer. Instead the purpose is often to incentivize the warrant holder. You can strengthen these incentives by making the value of the warrant conditional on certain events that you want the holder to push for. Or you can write it such that it won't be costly for you to pay off in case things go south. There are a whole bunch of possibilities.
In general if you want to know why a warrant is a certain way, you must start by remembering the most common purpose of warrants: to incentivize insiders.