Trump isn't going to give him anything anyways. There's no sense trying to suck up to Putin's puppet.When your hat in hand its probably not a good idea to insult the one your begging.
If I were Zelensky, I'd call Trump's bluff. Since Trump has proven that facts don't matter, as Zelensky I'd call a press conference immediately and say something along the lines of, "I am very gracious of President Trump's offer to send American soldiers to Ukraine to act as peacekeeping forces. He even gave me his personal assurances that these troops would not hesitate to engage the Russians in combat."