"There's an investigation taking place and we'll let that run its course before making any bold statements about that sort of thing," he said.
Hesson said the fact the early questions at a press conference today were about the pair's behaviour and not New Zealand's fine 40-run first test win at Eden Park "is clearly disappointing for the team and takes away from a superb effort over the last four days".
Hesson admitted he had seen television footage of Ryder drunk outside an Auckland bar on the night of January 25, and having to be helped into a taxi.
"It's not a good look," he said.
The second test squad will be named tomorrow morning. The most obvious contender to replace Bracewell as fast-medium backup, Canterbury's Matt Henry, is sidelined by a groin strain.
Another batsman may be needed in the group as cover for leading batsman Ross Taylor, who wife is due to give birth to a second child around the time of the second test.
New Zealand's world T20 squad was to be named on Wednesday. That would certainly have included Ryder, until a few days ago.
NZC have until Sunday to name the squad, under International Cricket Council regulations, for the tournament next month in Bangladesh.