User blog comment:Jrotc193/R.I.P. Gray/@comment-46.43.120.64-20130609185056/@comment-7418318-20130610080951

If those attacks really were lasers, they wouldn't even be visible and they wouldn't have the physical impact to punch through anything and leave a hole, so don't make any analysis of how a laser can or can't damage liquid please.

All we know is that those glare-spawn shot some elongated "something". For all we know they might still turn out to be physical attacks that leave a trail behind.

And even if not, calling them beams or rays, which are general terms would be far more fitting than laser, which is a very specific term (and in this case very unlikely).

Anyway, as we saw on Tenrou Island, there are some kinds of magic that can hurt even Juvia's waterbody. And Gray had no way of knowing wether those shots might be able to, so it makes sense for him to shove Juvia out of the way.

Furthermore, whenever an attack passed through Juvia's body, she was always aware of it, by seeing it before being hit, so it's likely that she can only let attacks pass through her waterbody, if she sees them coming. While she was already looking in the direction of the shot, due to Lyon's warning shout, she still might not have been able to react fast enough to save herself, even if the shot was something that can't hurt her waterbody.