His wayward subordinates in the Dollar Cabal believe that it is one of his hidden subordinates that is responsible for the marks.
So even though that subordinate has been showing weakness and indications that there is something wrong, it is not enough for them to come to the conclusion that he is dead.
He has only lost contact with them for two months. They need more time and more tests to determine beyond reasonable doubt that their boss, Diamond Dollar, is gone from their lives.
They were partly afraid and partly full of hope for their future because of the absence of their boss.
They are afraid that this is a test from that boss, so he is not dead. They are also afraid that Diamond Dollar is dead, and the person who killed him might come after them.