It's possibly safe, but I am extremely leery of heat lamps personally. Though I do use them depending on situation. If it's nice enough outside, I just use heat plates. If it's dipping down really cold, I will put a heat lamp on to warm the space within the brooder enclosures I use.
I would think anything metal should be "safe", but be careful with whatever coatings might be on the metal. Some paint might want to burn that close to a heat lamp.
I don't use a heat lamp in the house ever. If you're going to brood any amount of chicks more than one time, I'd really suggest a heat plate personally. They seem to be getting more and more available. Our local farm stores sell them now and it seems like I see them on Facebook Marketplace fairly frequently.