The timezone is hardcoded in the org.springframework.batch.admin.web.JobExecutionController class.
In this class you see the following hardcoding of timezone to GMT all over the place...
model.addAttribute(new JobExecutionInfo(jobExecution, TimeZone.getTimeZone("GMT")));
I think it would be better to default the timezone to the users locale and make it possible to override it using a configuration setting. I'm in a GMT+10 timezone so displaying GMT times makes times appear way off and there is no indication on the web page that the time is displayed in GMT.