Is there anyway to make the Rom ignore slider function?
Just going to ask so that we're clear on this, English is your first language, yes?
Now, I'll try and explain it again. This ROM and it's Launcher were designed (by the original MIUI Developers from China) for the N1/Desire. And as such, the Launcher was not coded to recognize a physical keyboard. Ergo, the phone unlocking when the Droid physical keyboard is slid out is an unfortunate side effect that, as of yet, has not been "fixed". And unless Zen and/or MO reverse engineer (keep in mind, reverse engineering is not the same as porting) the Launcher to work specifically for phones with physical slide out keyboards, I don't see it happening anytime soon.
Again, it has little to do with the ROM and is mainly a Launcher issue, but since the Launcher is designed to work only with the MIUI framework (hence why it will not work with another ROM), then your only alternative is to use a different ROM if it bothers you so much/ is so important to you.
Now, you could also try using a 3rd party app to change the lockscreen (Widgetlocker), but I'm unsure if that would actually work or not. I have a feeling that the issue would still pop-up as I think Widgetlocker depends on the normal lockscreen to work properly. But again, I don't really know this, it's just a hunch.