Due process in dismissal for strike-related illegal acts practice question

Delta Tools, Inc., a company in Davao City, has its workers represented by the Progressive Workers Guild (PWG), whose officers include the union president, vice-president, and secretary. In March 2022, a bargaining deadlock led to a strike. Delta claimed that during the strike, certain union officers and members blocked the entrances to the company premises, preventing non-striking employees from entering. Relying on affidavits and photographs, Delta identified 30 union members and all 3 union officers as participants in the alleged illegal acts. On April 5, Delta sent a letter to the identified employees, directing them to explain within 24 hours why they should not be dismissed for their actions during the strike. Three days later, on April 8, Delta sent a notice of dismissal to all 33 employees. The dismissed employees filed a complaint for illegal dismissal, arguing that they were not given ample opportunity to defend themselves. Delta countered that it complied with due process by sending the notices. Should the dismissal of the union officers and members be upheld? Explain.