Flatbusher, there are many different opinions about different types of dairy products.
Some shittos are meikil on butter and some on cheese. On a practical level, soft cheeses not labeled as Cholov Yisroel are not g’vinas Yisroel, because the OU goes according to the shittah that it’s not required, but it’s a machlokes. Some are not makpid on powdered milk because there is a shittah which holds that way . There’s a machlokes whether one must be machmir on keilim if he’s machmir on not eating Cholov Stam.
In short, probably most combinations of chumrah/kulah have a leg to stand on. Whether the individual decided on his own for arbitrary reasons, went through the sugya, or asked a shailah, is something you would have to ask him or her.