Probably because the blog post is an advertisement for their product, which already allows you to implement bastion hosts as you describe.
From the bottom:
> Databases do not need to be exposed on the public Internet and can safely operate in air-gapped environments using Teleport’s built-in reverse tunnel subsystem.
They've been around a while, it actually seems quite cool. Bastion hosts are simple to setup, sure, but Teleport adds a whole bunch of porcelain on top, e.g. integration with SSO, web UI for administration, etc.
Haven't used them myself but I wouldn't be against trying it if in the market for something like that.
Probably because the blog post is an advertisement for their product, which already allows you to implement bastion hosts as you describe.
From the bottom:
> Databases do not need to be exposed on the public Internet and can safely operate in air-gapped environments using Teleport’s built-in reverse tunnel subsystem.