I really do not see any point in impeaching judges without real evidence of wrong doing. There is no way they will be convicted. And trump never seems to be able to come up with the evidence.All of this is true. Saying he wants to impeach a judge is among his rights, Roberts has a right to say it is wrong. Neither of them have the power to impeach anyone or to stop Congress from impeaching someone if they vote in articles of impeachment. Neither of them can force 2/3 of the Senate to vote to convict and thus remove the judge either. If the Senate does vote to convict on the articles of Impeachment after a hearing the SCOTUS cannot save him even if they think it is "wrong" to do this. It isn't within their power to stop the checks and balances that were designed into the system.
But talking about it a lot, even without evidence, can gin up the right wing terrorists, and get some judges killed. So I do see the point in that.