There's enough heat to lift or damage a gold or silver veneer.
Yes, I believe you. Without getting mind numbing technical, there is a huge difference between gold plate/veneer, gold filled and solid gold.
Gold plated items are made by using electricity or chemicals to deposit and bond a very thin layer of gold over another metal or other type of base. This bond can often be broken by heat, pressure or wear.
Gold filled items are those where an actual layer of gold is pressure bonded onto another base metal such as brass. An example of this would be older pocket watches. These would be guaranteed to wear for 20 years due to the thicker layer of gold over the base. A genuine gold filled object can normally take a good bit of heat without damage.
Solid gold is (mostly) a mixture of gold, silver, copper in various proportions depending on the color and karat desired. Solid or alloyed gold, has high resistance to corrosion and can take temperatures of around 2000 Fahrenheit before it deforms. Your pipe will be long gone before you could come near to harming a solid gold tamper to tamp tobacco.
This is all off the top of my head, but I have a lot of experience with this so it should be close enough for government work.