Michael Flynn on/in foreign policy

An interesting read. Who knew the Lieutenant General fired by President Obama was being considered as a VP candidate for Trump?
https://foreignpolicy.com/2016/07/12/trumps-possible-vp-believes-isis-could-conquer-the-u-s-and-drink-americans-blood/?fbclid=IwAR1Bx8-fj9Zq-z_3i1R5ZPIwsxo4_sTOPA_1zLABxHRFVco_XTtiYOls9zg

Shared guilt tends to result in either denial or doubling down. So, why was it important to John McCain to deny his prior association with Michael Flynn? Was the IRI a front for the CIA?