Arkie was careless
Arkie was described in series as very skilled, careful and clever drug-trafficker, was even compared to Jackal.
But if fact he was quite careless and stupid.
First of all, careful criminal would never fly with drugs via Bangkok, where there is death penalty for drug trafficking. Yes, his plan was to stay away from Kat in airport,to pretend to be stranger to her, but who would guarantee that his plan will work ?
Plus, they had to go thru Thai customs twice, which made risk even higher.Clever man would give some excuse why he cannot fly with her and why he has to join her later in Australia to collect drugs.
Second - his fingerprints were all over drug packages. If he was arrested with Kat,( or police would found his identity later) it would be impossible to deny his involvement.Careful criminal would work with gloves and wipe off all his fingerprints from suitcase too .
Third - he booked same hotel in Goa three times, which was super-stupid. Goa is a big resort, it is not hard to find different hotels every time .
Not so clever after all, huh ?