The main problem for every new user is always looking for safety by using one wallet and that is the main wallet.
When he participate in any program, that wallet will be sent, so it is very possible that at some point there will be a new program that is actually misleading, so the wallet provided will easily be hacked. But actually, it would be a very good lesson for him to remember that don't carelessly give or place your main wallet in any program that you don't trust, especially for airdrops which are often misused.
Just sending an address for the purpose of participating in a campaign or airdrop is not a big problem, because from the address alone it is not easy for hackers to track the private key or seed phrase... but what becomes a big problem is when the main wallet is connected to a third party application which will actually making the security of the private key or seed phrase very vulnerable...
I can't recommend using a main wallet (with a large balance) to participate in campaigns or daily needs... as long as creating a wallet is easy and free, it's a good idea to create more than one for security and privacy purposes.
To avoid unwanted things, it's better to use another wallet to participate in airdrops, testnets and the like. To avoid something we don't want. It's certainly better. Avoidance is the best way, rather than regret later because of the lack of understanding experienced by the beginner.
There are many ways that can be misleading and there is no harm in not revealing the main wallet. At least there is an additional wallet that beginners can prepare for the event they want to take part in, because there can always be mistakes made by beginners themselves.
Even though it is true that it is not easy to hack a wallet because of good security, it is important to avoid mistakes made by beginners because fraudsters are clever enough to trick them in many ways.