No Caliper Pin Dust Boot?

2007 Mazda 5
My friend's Camry's front brake pads have uneven wear problem on both sides (100K+ miles). We found caliper pins stuck and no grease (no broken boots). A healthy dose of CRC brake grease fixed the problem.

While I have tools scattered all over the garage floor. I've decided to inspect MZ5's front brakes at 35K. I'm suprised to find no dust boot and pins are exposed.

This is the first vehicle with floating caliper I've seen without dust boot. Would exposed surface of caliper pin be a long term problem (dust, rust)?