I think it will be a good patch.
It's true, as some users mention, there are cases where the following posts make sense or are useful for the topic. But, normally this only applies to the OP. I know that configuring a way for this alert not to appear to the OP will be more complicated, and in the end it has little practical effect. So I think this is fine.
Congratulations on yet another excellent job.

How about automatically merging them? Like this:
The post is untouched, but the black parts aren't shown anymore. Now that I type it, I realize this is probably much more work to do. And even more work if the second post is on a new page.
This should also work fine with "Reserved" posts, and since posts aren't really merged, the post size limit shouldn't be a problem either. If the new post doesn't count as a bump, rule #32 becomes obsolete

This would involve a lot of work changing the SMF. And in some cases this wouldn't make sense, because double posting is useful (as some members mentioned).
So the alert solution is the most appropriate.