Here's my theory about the Timekeepers: They're not trying to prevent the recreation of a multiverse; they're trying to keep their timeline isolated from the multiverse.
I think the rest of the multiverse is still out there, and the Timekeepers are trying to keep their timeline under the radar, and safe from the influence of the rest of the multiverse. But when a branch passes the redline, it becomes prominent enough to attract the attention of, or draw close enough to, other realities.
My theory is this explosion of branches will cause the rest of the Multiverse to finally take notice of this isolated strand of time, that we know as the MCU.
I think the rest of the multiverse is still out there, and the Timekeepers are trying to keep their timeline under the radar, and safe from the influence of the rest of the multiverse. But when a branch passes the redline, it becomes prominent enough to attract the attention of, or draw close enough to, other realities.
My theory is this explosion of branches will cause the rest of the Multiverse to finally take notice of this isolated strand of time, that we know as the MCU.