The little-known property developer and the US president’s son were all smiles when they shook hands on Valentine’s Day within the gilded walls of Mar-a-Lago on a deal they claimed would bring a Trump Tower to Australia’s Gold Coast . But that dalliance has been dashed in less than three months, with the developer now claiming the Trump brand is now too “toxic” to work with – and the Trump Organization responding that their local partner had provided only “empty promise, after empty promise”. After posting a picture of himself shaking hands with Eric Trump in February, Altus Property Group’s David Young wrote effusively about a Trump brand that he said was synonymous with luxury and quality, one that would help him build the tallest tower and “the best” resort in the country . The Trump Organization’s executive vice-president and the US president’s second son tweeted an image of a proposed $1.5bn shimmering monolith emblazoned with his family name rising like a mirage above the towers of the “glitter strip”.…