Simultaneous speech translation (SiST) requires balancing translation quality and latency. While most SiST systems follow machine translation assumptions that prioritize full semantic accuracy to the source, human interpreters often omit less critical content to catch up with the speaker. This study investigates whether omission can be used to reduce latency while preserving meaning in SiST.We construct a dataset that includes omission using large language models (LLMs) and propose a Target-Duration Latency (TDL), target-based latency metric that measures the output length considering the start and end timing of translation. Our analysis shows that LLMs can omit less important words while retaining the core meaning. Furthermore, experimental results show that although standard metrics overlook the benefit of the model trained with proposed omission-involving dataset, alternative evaluation methods capture it, as omission leads to shorter outputs with acceptable quality.