Which in this case is equivalent to 'if you owe 10k to Bank its your problem, but if you owe 10M its the bank's problem'.
One way or another Mozilla relies on Google remaining its customer for vast majority of money, while Google being their biggest competitor who eats out ever more of Mozilla's market share every year, further reducing any reason for Google to remain their customer going forward.
They've had other customers in the past and present, and could have others in the future. Should they take less money to not take the money from Google?
This idealism is nice but if you remove privacy unfriendly customers you rule out basically every customer and don't have the money to make a browser at all. Behind Google are Bing, Yahoo, Yandex, and Baidu before you reach duckduckgo who somewhat respects privacy.
