Has the time of the discovery been released?
Forensic teams might have been called to check around the perimeter (to see if there was any evidence of where and how he entered the water, presumably, not sure how far you could get with when). And if the body was left in the water until there was a forensically checked clear path to move it along, then the sequence and timing of events might not be that clear to outsiders. JMO
If a body had been in the water for the whole 2 weeks, then it is likely to be in a very poor condition. So perhaps (JMO, and with no particular expertise) initial assessment that linked this to the search for RO would perhaps be height, frame and sex, race, hair and clothing and other personal effects?
Formal identification would be either by dental records unless the person they were matching to had no fillings and had never had a dental X-ray (inadequate reference point) or by DNA to reference sample retrieved from items at home or, if none, then matched to parent/s (or in this case maybe his own medical records as it's possible he has been karotyped or they might just have bloods retained in hospital lab). Fingerprints not much use for bodies that have been in water for a long time, even if there were a reference set, as the flesh macerates,