An exploit is anything that gives you a unintended advantage.
Board flipping is clearly an exploit. The mission board generates a limited set of missions, some of them good some of them merely okay, the idea being that in ED you are supposed to make do with the hand you are given. Because of some tehnical limitation, you are able to bypass this by connecting to a different server to cherry-pick only the good missions. If you take advantage of it, you are clearly exploiting, also known as cheating.
That Frontier are unable to do anything about it doesn't change much to what you're doing. Combat logging is also an exploit they are apparently unable to do anything about, doesn't make it any more legit.
The guardians were added by design. Board flipping is not by design. It is enabled by the current implementation, but that is far from being the same by design.
If you are going to call board flipping an exploit then you first have to deal with the fact that we are allowed, at will, to change game mode. And we are not limited from what we can do in either game mode and that includes but not limited to view mission.
Then I can agree that way FDEV have implemented where and how missions are generated are sub-optimal design, that make mode switching work with alot quirks....
Because if think this is an exploit, then what about all those missions/tasks ingame that reset when you switch modes? Not limited to these,
Killing skimmers? They do not respawn, so the fastest way to complete all the skimmer is to "mode switch",
Doing the Guardian ruins puzzles to get blueprints, once completed, there is no reset to the puzzle, so fastest way to reset these are to "mode switch"
Doing surface scans missions, same here, there is not reset, so once again fastest way to reset is to "mode switch"
Are any of these cheating? Exploiting? Or just the result of a bad game design? Many of these have been well known things to do and yet, FDEV still implements more of these kind of game design, among the latest is the Guardian "puzzle" you need to do over and over to get Guardian blueprints.
There are other ways to reset above scenarios, but they are way slower than just a simple "mode switch".... and even these does not make it any more "immersive" than what the "mode switching" is doing....
So here you have it, you call the added Guardian as DESIGN, so then I guess you approve that the design of Guardian puzzles for getting blueprints. Please enlighten me and other on how do these without relying on anything that with your logic, can be considered an exploit. And please consider "we do not want to waste players time" ... Also, while you are at it, please enlighten us how this by design is good for player playing together, exploring, testing etc,. etc the puzzle, when only one in the group will get the prize, one blueprint. In essence, making it almost useless to complete these puzzles as a group.