They have themselves changed the Bible, deleting certain scriptures that they had previously included in their bible is just one example.
God has allowed mismatches in the various copies of the original Bible texts that have survived that are being used as the source text in Bible translations so a resulting version of the Bible from source texts is subject to what source text are used. The WT has qualified changes to the NWT by citing older source texts now being used and other reasons, but again, Bible translations rely upon various versions of ancient source texts. Knowing various languages, I will tell you that translation requires interpretation and for someone that does not know the base language and is only reading the translation is missing a lot of flavor, nonetheless, the substance is there. I am happy with the NWT. Keep in mind that you are not reading the Bible sort of speak but only an interpretation of what the Bible says from the copies of original source texts that have survived.
They hold to this view by their ever changing doctrines, both in re-interpretations and flip flopping on ideas.
No they don't. They qualify what they mean in the article that you refer to with the Scripture they cite in the article.
This is what they conclude when there is ever changing truth. They get to choose what is right and what is wrong by their own interpretations. There are many examples of them changing their minds about what is right and what is wrong, I am sure you are familiar with some of them.
No they do not. That is what you say that they conclude. JW do not decide for themselves what is right and wrong. They look to the Bible. What is true is that JW have sometimes have had to change what they believe the Bible means but they never decide for themselves what is right and wrong independent from the Bible which is what they mean in the passage you quoted above in connection with people they refer to as doing bad inspite of what the Bible has always taught is bad. Some people use JW change in what they teach as a pretext against JW so they can justify whatever they want is right and wrong . But JW have done no wrong in adjusting their beliefs in light of facts and clearer understanding. The Bible is written in the form of an ironic poem crossword puzzle and there is nothing bad or wrong in not understanding it all but trying to solve. If you have ever done a crozzword puzzle you know that you have to write with a pencil.