Can't add valid RSA key, marked as "invalid"

Dear Attlassian,

I'm trying to add the following rsa key at https://bitbucket.org/account/user/mr_big/ssh-keys/ page, but I get the error "That SSH key is invalid."

ssh-rsa AAAAB3NzaC1yc2EAAAAFALVoPe0AAACBANGt8z5XY26IqSBu/w/yGFvWKBCo+jFdBovDr0B9e7FyAhQZhis2x6hGtBkm+WJqTXzBZQX2LGBC7gDZjMdtttBxWUzt5nECMWodprtXpQLa1I97K7FofxxcYdlo1eCeJW0p9KdlLXMgTvCD+0Vo9WW9wR8Wzld18btghgZ3UxWn

The response "That SSH key is invalid" is obviously not true, I'm using the same key at a dozens of site without problem, and I was using it at bitbucket before 2016 as well.

Sadly it seems like Bitbucket decided to not support rsa keys shorter than 2048bits. The above key is a 1024 bit key (generated by a hardware token).

Expected result:

the site should tell the user, that the rsa key is valid, but not long enough, so it is rejected on administrative grounds.