Trump is shallow as a mud puddle. Admiration is not in his wheel-house. Only transactions. He fears Putin because Putin likely has kompromat on him that he dreads becoming public. Bladder refers to the peepee tapes it has been alleged Putin has on him.
I think you do not read him right. Yes, he is transactional, but he craves admiration of men he sees as strong and powerful. Putin pretends to respect him. If Trump felt that Putin blackmailed him (with peepee tapes and such) he would show unbridled hate. Doesn't mean that they do not exist.
Wanting the admiration of other men is not the same as possessing admiration for others.
Trump wants admiration from everyone, but he does not admire everyone (he despises his MAGA base, for example). If he is sure some powerful people do not admire him, he declares them inconsequential, but they are still on his mind. Putin is someone who is constantly on his mind in a positive way.