1 Kings 1:41-42

1 Kings 1:41-42King James Version (KJV)
41 And Adonijah and all the guests that were with him heard it as they had made an end of eating. And when Joab heard the sound of the trumpet, he said, Wherefore is this noise of the city being in an uproar?
42 And while he yet spake, behold, Jonathan the son of Abiathar the priest came; and Adonijah said unto him, Come in; for thou art a valiant man, and bringest good tidings.

American English Bible
41 Well, when AdoniJah and all his guests heard the commotion, they stopped eating. And when JoAb heard the trumpets blowing, he asked, 'Why is the whole city in such an uproar?'
42 Then, while he was still speaking {Look!}, JoNathan (the son of AbiAthar the Priest) came in. And AdoniJah said: 'Come on in! Since you're such a powerful man, you must be bringing good news!'

These are my thoughts, please share yours.

41 This was David’s son who was trying to steal the throne. Them being guests did not mean they all supported him overthrowing David, they may have been told by him that he was to be king, them thinking David would give the kingdom to his eldest son which was the normal. They also may have come for free food. Trumpets were blown for important reasons, worship and war were two main reasons, the new king is the reason it is blown here.

42 It mentions Jonathan being a son of the priest but does not mention him being a priest himself, so he was not yet a man in God’s service. He truly was not worthy to bring good news. There is no good news outside the will of God.