I generally prefer to place web/whirl ignore units in squad number two, for the simple reason that it makes it easier to plan where the squad goes on some maps which have those things behind switchnodes.

Simple examples:
If the webs are behind the initial direction of the switchnode, then simply put squad 2 on the tent for that path and squad 1 on a tent following a different path.
If the webs are behind the second direction of the switchnode, then you can still place squad 1 and 2 both on the tent for that path. Squad 1 passes first and takes the initial direction, squad 2 (with Nerine) heads for the webs.

Putting Nerine in your first squad rules out that second option, so it's simply less versatile.