This could theoretically be achieved by either means. The question was specifically why a vertical landing is favoured over a cushioned inflatable landing. Mus

This could theoretically be achieved by either means. The question was specifically why a vertical landing is favoured over a cushioned inflatable landing. Musk has stated in the past that they're looking to eventually use this tech to create rockets which can be used on Mars, hence why parachutes and inflatables are out of the question.