Be kind to the "club pro", but do ignore his advice.

I use that technique whenever I can. Sometimes, a particular situation won't accommodate it. The last one I had that didn't like it was a H9 Twist 40 (3 years ago). It glitched intermittently, so I ran the antenna outside the fuse, and it was happy. Usually, when the fuse has enough space to hold the antenna, it's not a problem to have it inside. Range testing will let you know.