Hi, thanks for finding a way to re-enable Tampermonkey. Once the scripts are exported you can also install Tampermonkey BETA from the Chrome Web Store since it is not blacklisted (at the moment).
https://chrome.google.com/webstore/detail/tampermonkey-beta/gcalenpjmijncebpfijmoaglllgpjagf
I have no idea why Tampermonkey is considered to be malicious. I guess some algorithm wet wild.
I already contacted the review team via my Opera extension developer account. Hopefully they can tell me more about this issue.
https://github.com/Tampermonkey/tampermonkey/issues/635
Sorry for any inconvenience.