It may not be melting, but its outgassing from the heat. Which means it is deteriorating. And i dont think those fumes are healthy to inhale either

Better have ventilation!
Is it likely safe to use just for a short time?

Yep, as long as there isnt anything flammable in front of the beam of light that can catch fire....

And you better not pair it with my GU10 "death ray".

Its Double Death Ray, the ray kills and the smoke (from the smoking gun) kills too