I mean, no matter how hard one tries, there is simply no way to deny the reality of this training for the rebuilt Temple
In light of the completed work of Christ, is what you say they are doing a good thing?
However, the Scripture is clear on two other issues: God is not done dealing with Israel and the Jews, and God judges sin.
We know from God's Word that the Jewish temple will be rebuilt, and we know from God's Word that the Jews will be carrying on the rituals and sacrifices that they performed until their second temple was destroyed by the Romans in 70AD. We know this will happen because God said it will.
The fact that the descendants of the Old Testament Levitical priests are now in training to serve in the newly rebuilt temple is neither good nor bad; it is something that God has decreed will happen, and therefore it will come to pass and, as we are witnessing in our time, the players in that Tribulation scenario are making the preparations which will result in the fulfillment of Scripture.
God is not finished with Israel; His covenants with them are still in effect and are eternal, and the Tribulation period which is, as God put it, "The time of Jacob's (Israel's) trouble", will be a time when 144,000 Jewish people, who have come to salvation in Christ, go throughout the world spreading the Gospel, and it will be the time when, as God put it, "All Israel shall be saved". The day will come, as God promised, when the surviving remnant of His people will come to know Christ as Savior.
The fact that this training is occurring is merely another brick in the wall of ongoing fulfillment of Bible prophecy. There is no value judgment to be assigned to it; it simply must happen because the Sovereign God has decreed it.