I think that is pure speculation. I don't see anything in the article that clearly support that it was bribery and not the money in support of local conservation that could be expected. Just like the money the Chinese require for giant panda. But if the $50,000 really was bribery then of course Jurong should not go along. Unfortunately I guess bribery is much more common in zoos than we know. Especially in countries where bribery in general is common.
The Philippine Eagle Foundation are already successful in keeping and breeding Philippine eagle and they have a large facility with plenty of space. There is not really anything major Jurong could add in captive management of the species. Unlike if they started a project with for example Javan hawk eagle where we still know very little about captive management (I think it still hasn't been bred in captivity despite an attempt of starting a breeding program but I believe few if any pairs have been kept under the high quality conditions now possible in Jurong). What Jurong do have is money but they can provide economical support to in-situ projects no matter if they keep Philippine eagle in their bird park or not. All in-situ projects that I know they currently support are in Singapore via their
WRSCF foundation and most of the species they support are only seriously threatened when you look at it strictly in Singapore (rhinoceros hornbill, Oriental pied hornbills and banded leaf monkey have large populations elsewhere). I'm certainly not saying that the great breeding records for many threatened species in the bird park or their in-situ projects in Singapore are irrelevant because that would be very wrong. Just that they easily could expand to also support in-situ projects in other countries for species they don't keep in the bird just park like
Fort Worth Zoo have for the Philippine eagle. That is especially relevant when large and successful facilities already exist for a species within its native range.