While I don't think this "forces" a vegetarian diet on the employees, it is placing the employees in a situation where their company is promoting a particular ideology/lifestyle/diet through financial motivation. Dining is generally reimbursed during business travel due to the (often significant) increased cost of having to exclusively dine out, so the option for the employee is to eat vegetarian or accept additional…
In this case exacerbated by the fact that said lifestyle or ideological change involves one of the bare necessities (since all of the "equivalent" examples I've seen do not).
That's highly debatable. A good part of the world lives completely fine even without this bare necessity.