So a few cut marks makes them think that hominins existed further back than previously believed. I'm not saying it's impossible that hominins were around back then. I'm just saying that this info isn't enough to put too much into. For example, we already know examples of bite marks leaving straight line marks in bones.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6188009/
Long and straight bites from tyrannosaurs are typically left as a result of scrape feeding where the premaxillary teeth are drawn across the cortex (Hone & Watabe, 2010) and usually leave multiple subparallel traces that are broad because of the D-shaped nature of the teeth and these are therefore rather unlike mark 2.
“Fossil data were then statistically compared with a sample of 898 BSMs of known origin, including: 405 cut marks from a variety of stone tool types and raw materials53; 275 tooth marks from crocodiles and five species of mammalian carnivores54; 130 trample marks produced by cows on substrates including sand, gravel, and soil55; and 88 percussion marks from both anvils and hammerstones56.”
The original study source:
https://www.nature.com/articles/s41467-025-56154-9#Sec6