pinch of salt

Kazuo IshiguroのWhen We Were Orphantsを読んでいます。
There was the moment, for example, when at the dinner table he said quite suddenly to my mother: 'Did I tell you, darling? That fellow came back to see me, that representative from the dock workers. Wanted to thank me for all I'd done for them. Spoke jolly good English too. Of course these Chinese always speak very effusively, these speeches of theirs have all to be taken with a pinch of salt. But you know, dear, I had the distinct impression he meant it. Said I was their "honoured hero". How do you like that? Honoured hero!'
上の箇所に出てきた "pinch of salt" は "with a grain of salt" を連想させますが、どうでしょうか？　辞書を見ます。
・Wikitionary: (figuratively) Caution, doubt, consideration. Take anything he tells you with a pinch of salt, he's an inveterate liar and mixes truth with his fiction liberally.
・Cambridge English Dictionary: to not completely believe something that you are told, because you think it is unlikely to be true: You have to take everything she says with a pinch of salt, because she tends to exaggerate.
"pinch of salt" を項目として掲載している辞書が余りありませんでしたが、下記のように多くの辞書で "with a grain of salt" の項で "pinch of salt" と同じと説明しています。
"take something with a grain (or pinch) of salt" ・Oxford English Dictionary: Regard something as exaggerated; believe only part of something.: take a stock tip with a grain of salt