Wait, now I realising what's still about it. I thought it was about outstanding payments to the players. Now I am reading it again and it's about not having a contract for the past 4 series.
The WIPA could have easily boycotted some earlier series, like against India. Why are they boycotting it now? It's somehow highly likely they decided to not boycott the India series, but the Bangladesh series. I feel a bit sorry for the Bangladesh team. I mean they went to travel to West Indies, played a warm-up match and for a couple of days ahead of the first Test match they're coming up with this.
They could have easily said it before Bangladesh came to West Indies (they came during the ODI series against India), that they would boycott the series if no contracts would be made.