Australian umpires Simon Taufel and Steve Davis, along with British match referee Chris Broad, have complained they felt deserted by their security escort during the attack.
International Cricket Council boss Haroon Lorgat has suggested the officials need to be "more rational" about their experience but Bayliss backed their version of events.
"They told the truth as they saw it," he said.
"There's probably a big difference between some of the comments that have been made between some of the people that weren't in that convoy to the ones sitting in the bus.
"In hindsight, there just wasn't enough security and ... even the police chief and the security people have actually said there was a lack of security."
Returning to his homeland for the first time since gunmen opened fire on the Sri Lanka team bus in Lahore last week, the Australian said