one reason is that while it was an ecb request as far as i know, glos were short on players i believe so wanted it anyway.
plus its happened before, strauss played for somerset last year because middlesex didnt ahve any 4 days game before the test series. basically we jsut loaned bopara to glos for the day, nothing wrong with that, happens in all sports. if it was called a loan then there is no problem. though i really dont think bopara is match ready yet, not many people at essex seemed conviced on sunday either though no one knows why he had a break