Plausible deniability yes, but even just safety. If I don't engage with a topic in a detailed manner, it's very unlikely I'll say something wrong about it, that could later come back to haunt me. Remember "the internet is a series of tubes"? The guy was hammered for trying to understand a complex topic - and he wasn't even dramatically wrong, just used a metaphor (almost certainly thought-up by someone in his staff) that was just excessively reductionist.

The media playing gotcha has made it fundamentally dangerous for a politician to be publicly wrong on any topic. The reaction is to avoid engaging with complex issues.