The protocol currently allows thresholds up to 100% (see MAX_THRESHOLD) for collateral assets. This is unhealthy because liquidations/absorptions can only happen if ltv > threshold. Furthermore, the liquidation penalty at ltv >= 100% is zero, i.e. there is no liquidation incentive and consequently troves with such high thresholds can effectively only be absorbed.  
Set the MAX_THRESHOLD to 90% in order to facilitate profitable searcher liquidations in any case.
