You must not know of Amitabh and the Shahrukh -- they're not some smalltime actors that need to get a leg up. This would be like Tom Cruise and Brad Pitt offering to be servers at Jeff Bezos' daughters wedding. It's absurdly subservient.
In India, it's common for hosts to serve food as a sign of respect to their guests. Close friends and family of hosts also join. This only showed the closeness of the relationships among Mukesh and other stars. Seeing it as a subservient act isn't accurate, no big star would sign up if it were so.
Beyonce did a show too. So did a lot of Bollywood celebrities. These celebrities do paid gigs at these ultra rich wedding parties.
https://www.wmagazine.com/story/isha-ambani-wedding-india-hi...
Not too long ago, it used to be that family and friends would get together to cook for the wedding.