Mr. Sudhama....
Let me try to put my views on your question on Lord Krishna's acts of using Adharma... to finish the war...
Lord Krishna's main objective was reestablish DHARMA..... to do that ..... he didnt mind even doing ADHARMA... to render justice.....
this prompted him to venture into all adharmic ways to eliminate giants like Bheeshma, Drona, Karna and even Duryodhana finally....
( infact he will ask Arjuna to shoot an arrow on Purisiravas...who actually will be fighting another guy... Satyaki and not Arjuna... but still Srikrishna pushed Arjuna to shoot that arrow.... because... Satyaki was representing the Dharmic forces ..led by Yudhistira.... )
Probably this could be the reason...
There is also a saying in Tamil...
THANNAI KOLLA VANDHA PASUVAYUM KOLLALAAM...