Thank you so much, Kevin!

Snip suggests the use of scissors to cut something. Snip out suggests using scissors to “cut out” a part of something. In essence, cut a section and remove it. You might use it to describe certain surgical procedures, like “snipping out a section of tumor for analysis”. In this context it refers to cutting out a length of DNA from the helix (with the goal to insert it elsewhere). It likely isn’t using scissors (!) but the meaning goes beyond the tool used, to give a feel for the action rather than a physical description of events. Basically, there isn’t a better way to say it