Nothing remained secret in a Temple full of Force-sensitives.
It'd only been five minutes since Obi-Wan pressed a kiss to his Master's forehead and departed for his morning classes, and already no less than seven Masters had levelled decidedly penetrating looks at him. Master Windu's hard glare in particular projected the inherent threat of 'if you hurt him...' louder than words ever could.
But despite Qui-Gon's unfortunate past, from Xanatos through Tahl, Obi-Wan instinctively understood a truth his Master's friends didn't seem to grasp.
Obi-Wan was never going to be the one to leave. And it wouldn't be Qui-Gon who got hurt.