Using rnav for ils fixes

edit: for context this all was on a g1000

I had a stage check flight and everything went smoothly until I had to do an ils approach with an ahrs failure. I don’t think the ahrs failure was the reason for my mistake, but I had to report a fix which was an intersection between the localizer and a vor radial. To do this I put both frequencies in nav 1 and nav 2 and switched between both green cdi’s to find the intersection. This fixation and a lot of other smaller related mistakes caused me to go full scale deflection on the localizer, and I failed.

After the flight, my examiner said there was no need to switch between navs to find the fix because I could’ve just used gps to identify it. I knew it was an option, but I thought on ils (or vor) approaches you can’t depend on gps to find non gps fixes like intersections. I’m not blaming my failure on anyone but myself but I know if I had just looked at the gps that I most likely wouldn’t have failed.

My question is during my actual checkride am I allowed to rely on gps to find fixes on green needle approaches or did I do the right thing? It wouldn’t make that much of a difference since now I know how to do both but I’m still curious.