Is it acceptable that 'fuel' is pronounced as 'fju:ə'

Yes, there is someone - your friend. All variations I've encountered have the "L", though the strength of it may vary. I dare say there is some dialect where you can barely hear it.

Generally speaking, it's not a good argument for the pronunciation of a word to say "I've heard it said like that once". The aim of language is communication, and it will aid communication if you pronounce words in a standard way, i.e. a way spoken by a large number of people.

Is it "acceptable"? Strictly speaking, if the people he's talking to understand him, then it's acceptable. That's how language evolves.

Is it commonplace and likely to be understood around the world? No.

Certainly personally I've never heard that before and would consider it quite strange. And I'm a native speaker so I don't know what kind of native speaker your colleague was listening to.