HDB lawyers Darrell Low and May Tan told the court that the board had been "reviewing available racks" since year 2000 - see 5 designs considered in the Facebook page "Development of HDB Clothes Drying Systems". Meaning, Yiap's invention could have been included in the survey. HDB dissed his creative effort as unsuitable, and proceeded to implement their own system in August 2001. Maybe the HDB had cherry picked the best of the features in rack systems they had come across, Yiap's ideas included.
But that was not the crux of the legal arguments presented in court. HDB said Yap only applied for the patent in February 2003. The technicality of timing was repeated by the lawyers in highlighting that potential patent infringement was suggested only in 2006, and the statutory time limit for filing a legal challenge, being only 6 years, had run out. Timing plays a crucial role in Singapore events because a walkover in Tanjong Pagar during GE2011 was decided by the tardy bureaucratic processing of another challenger's nomination papers. The losers have their own story to tell.
It was Justice Chan Seng Oon who mooted a more palatable justification for junking the intellectual property claim: that Yiap had calculated the load bearing capacity of his system to accommodate the weight of a human body, in case someone should fall while hanging out the heavy clothes to dry. HDB chose to save on the cost of engineering materials, and not incorporate the safety factor for the protection feature. Rather, they preferred to let their customers hang out to dry. The profit motive for a less robust design variant is consistent with the philosophy of the day, "what's wrong with collecting more money" ?