This is not true, it is both a platform issue and training issue. Since the platform has a safety, you must therefore also train in it's operation. Whether the safety is a hinderance or not has nothing to do with whether there is a safety to be operated or not to begin with.
Uh...the bolded sentence kind of makes my point. Because the "platform issue" goes away with training, in that someone who is remotely practiced on a 1911 can deactivate the safety subconsciously on the draw, it takes away the "platform issue".
There are a lot of 1911 fans on this forum that will tell you the drawstroke of the 1911 takes no longer than the draw of a Glock. Therefore, it is not a platform issue.