Hello @Algerie31,
I would like to ask you, why asking this ?
I mean, this is really easy to release them... You don't have a tons of pokemon to release in the bug catching, usually you catch rare tiers which are "rare",if you start to catch everything use the releaser inside the safari to avoid that. Since the ID is instant, you can release them in the next second and you don't have to wait between each release.
Sorry to be rude but for me this suggestion have no-sens and probably is due to some laziness.
For me that's not a good suggestion, again, sorry but there is no point to add that in the game.
Hope you understand,
Zesk'