Key phrase is "some will be unable" which infers that some will be able to transit. However I don't know how many "some" is nor do I know how many ULCC's there are or how many there are relative to other tankers
I like the EIA as a petroleum information source.
But without dimensions to reference, I have doubts about those very general statements.
Can you find a tanker with 100,000 DWT or larger with a draft at 15.2 or less meters?
It seems they are all in the +20 meter range.
As for ULCC, there are not very many in the world. None of them will fit through the new Panama Locks.
On the list above of the world’s supertankers, including those now out of service, the smallest is the S.R Long Beach at 214,862 dwt. It had a draft of 19.7 meters.
I found the Prince William Sound with one of the shallowest drafts of 16.8 meters for 125,925 dwt.
Can you find any supertanker, or any tanker of at least 100,000 dwt, that has a draft at 15.2 m or less?