I think bots could be coded to go through the interface though, right?
Yes, they can. But it's a question of whether it's worthwhile for bot owners/devs to do that because normally a bot that doesn't need to interact with the interface is easier to code and adapt to changes.
I totally understood the reasoning why these extra rewards shouldn't be available to bots. Sponsors aren't advertising to them.
About flagging the account, that would be... difficult. Say someone normally plays the account but at some point goes on vacation with no access to the internet and has the option to allow a bot to play on his Splinterlands account or delegate and chooses to run the bot. Should the account be flagged? I think not, just not receive the extra rewards if the bot is playing at the time.