“Samson said to them.” It seems that the woman’s father did not meet with Samson alone, but that other Philistines were with him. However, there are ancient texts that say, “Samson said to himself,” and that is reasonable and possible. It is actually unlikely that he would publically announce his intentions to “harm” the Philistines.
“This time I will be blameless.” The only other time that Samson attacked the Philistines was when he killed men to take their garments (Judg. 14:19), and it may be that Samson recognized that the Philistines he killed had not done anything against him that deserved death. However, “this time” he thinks he is justified in the “harm” he plans to do.