This finding is not really that surprising. Even adults have ear symptoms with a viral URI including ear fullness and difficulty popping the ear. Though adults do what they can to keep the ears clear by valsalva, swallowing, chewing gum, yawning, or proactive ear popping, kids may not even know what to do when their ear feels full or otherwise abnormal let alone blow their nose.
When the ears are not ventilating properly whether in adults or kids, it leads to ear problems including fluid buildup and even infections.
Why does this occur?
With a viral URI, the mucosal lining of the nose gets swollen leading to symptoms of runny nose, nasal congestion, and even nasal obstruction. However, this mucosal swelling does not just occur in the nose, but the eustachian tube as well which connects the back of the nose to the middle ear space. When the ear "pops", what one is doing is opening up the eustachian tube to allow pressure and fluid to drain from the ear into the back of the nose. That's why yawning, swallowing, or nose-blowing causes an ear pop normally.
When the eustachian tube mucosal lining swells up, it utterly blocks the tube preventing ear popping leading to symptoms of persistent ear pressure, clogging, fullness, fluid buildup and eventually even ear infections.
Read more about eustachian tube dysfunction here.
Reference:
Clinical Spectrum of Acute Otitis Media Complicating Upper Respiratory Tract Viral Infection. Pediatric Infectious Disease Journal: February 2011 - Volume 30 - Issue 2 - pp 95-99 doi: 10.1097/INF.0b013e3181f253d5
as well as directly from the 
