If the vendor value was on the Survey, you'd be able to follow the answer to Hide/Visible Survey Questions

Unfortunately, there is no way without scripting to accomplish this and I do not suggest solving this with scripting.

My recommendation is to create another Tiering Questionnaire Template by copying the Basic questionnaire and removing that question. You can call that tiering questionnaire "Key Vendor Survey" or something and assign it in the Tiering Questionnaires related list instead of the "Basic" when you send a tiering assessment to Acer etc.