That’s because they used civilian criminal forensics labs in addition to obsolete DNA testing techniques. The contemporary DNA testing techniques can be accomplished by any 3rd year biology undergrad student in an afternoon (provided they have unfettered access to the necessary lab equipment).
My suspicion is that they had ‘hot’ lab facilities in standby for necessary comprehensive testing. The SEAL team probably had DNA-lab-on-chip kit with them and preliminary results were established by the time they RTB’d. This probably resulted in the 99.9% certainty, i.e., 1:1000 profile. Then they implemented more sophisticated in-lab testing - at minimul mitochondrial DNA to establish familial relationship - which resulted in whatever probabilities were deemed sufficient, i.e., 1:100000, 1:1000000, 1:10000000, etc. Badda-boom, Bing! Bing! Bing! We have a winner, and he became clam-food.
The final confirmation probably took no longer than 4 hrs after Team 6 RTB’d. Reports are that he was sleeping with the fish w/in 8 hours of the operation.
Don’t you think they would recognize him? I mean, if he was laid out in front of them? The DNA is just a verification.