Thus is a move to make sure Open Source software developers and individuals cannot produce Kernel mode drivers.
No. This is a move to further prevent kernel mode malware, because it turns out trusting developers wasn't good enough. That it impacts OSS is collateral damage - and something that can be dealt with, at that - as while OSS is popular here on Slashdot, it's not much more than a blip in the wider Windows world.
The whole reason we're even going this route is that trusting developer signed drivers has proven inadequate. Microsoft started requiring developer signatures (cross-signed) in Windows 7. This significantly cut down on driver based malware, but it didn't eliminate it entirely. It just raised the barrier to entry. Instead malware authors would just eat the cost and buy a certificate, or the especially crafty/evil ones would steal another vendor's keys, as we saw with the Realtek case. Either way Microsoft has had enough of it. and hence Windows 10 requires that they sign off on all drivers so that no one can just ship a (obviously) malware-infected driver.
I don't mean to be snarky/belittling here, but if you think that Microsoft is doing this as a strike against OSS, then you haven't been paying attention to the wider world. OSS on Windows certainly exists, but OSS projects that require kernel mode drivers are exceedingly few and far between. Which is not to say that OSS isn't a threat to MS to some degree, but that threat is from Linux, not OSS projects that require a kernel mode driver running under Windows. MS's prime concern is further reducing the ability of malware to hang out in the kernel space, as once malware makes it there it becomes virtually impossible to identify, contain, and remove.
And yes, this definitely makes signing harder for everyone. By all indications that's intentional, as EV Certs make it harder to hide (you have to provide more information) and are harder to steal/fraudulently use. There are ways to work with that for OSS though, just as was the case with Windows 7, so we'll be okay. As Bruce likes to say, security is a process; it takes more than just the OS vendor to keep Windows machines secure. So this is our contribution to that process (whether we like it or not).