If the case cited is WAL-MART STORES, INC. v. SAMARA BROTHERS, INC., 529 U.S. 205 (2000),
then the case itself makes your point when it talks about bottles of Tide detergent:
The Court contrasts the lack of distinctiveness in product design
with product packaging
"The attribution of inherent distinctiveness to certain categories of
word marks and product packaging derives from the fact that the very purpose of
attaching a particular word to a product, or encasing it in a distinctive packaging, is most often to identify the source of the product.
Although the words and packaging can serve subsidiary functions—a suggestive word mark (such as 'Tide' for laundry detergent), for instance, may invoke positive connotations in the consumer's mind, and a garish form of packaging (such as Tide's squat, brightly decorated plastic bottles for its liquid laundry detergent)
may attract an otherwise indifferent consumer's attention on a crowded store shelf—their predominant function remains source identification. Consumers are therefore predisposed to regard those symbols as indication of the producer, which is why such symbols 'almost automatically tell a customer that they refer to a brand," id., at 162-163, and "immediately . . . signal a brand or a product "source,"' id., at 163."
529 U.S. at 212-213 [Emphasis added].
Looks to me like the examiner misunderstood the case. It clearly says that trade dress as packaging can be distinctive, and even uses a bottle as an example of this.
Now there is a part, later on, where the Court allows that there could be close cases between trade dress as product and trade dress as packaging, noting that the classic Coke bottle design could be product in the eye of a BOTTLE COLLECTOR or someone who fancied the classic design as otherwise stylish.
"There will indeed be some hard cases at the margin: a classic glass Coca-Cola bottle, for instance, may constitute packaging for those consumers who drink the Coke and then discard the bottle, but may constitute the product itself for those consumers who are bottle collectors, or part of the product itself for those consumers who buy Coke in the classic glass bottle, rather than a can, because they think it more stylish to drink from the former." Id.
And the Court does allow that in cases such as that "we believe that courts should err on the side of caution and classify ambiguous
trade dress as product design, thereby requiring secondary meaning." Id.
But even if that's what the examiner had in mind, it seems an incredible leap to get from that statement to a conclusion that every drink bottle is "ambiguous" as to product vs packaging and therefore demands a showing of secondary meaning.
Surely Justice Scalia couldn't have meant the Coke bottle example to have that effect! The example is merely a way to show how product and packaging could conceivably merge, but it hardly shows this in the context of a new mark! The classic Coke bottle was distinctive long before it became "classic" -- in fact, it would not have become "classic" if it had not been distinctive, no? And further, it could not have been "classic" without being around long enough to develop secondary meaning and be recognized
for its shape, making the whole question moot in any event! So it just doesn't work to use that as an example of new trade dress which is "ambiguous" as to the package/product distinction, and it certainly doesn't follow that drink bottles are inherently unable to be distinctive.