I think this is a storm in a tea cup.
The rubbers are there to locate the anti roll bar, and do it silently. That is it! If they are lubed or not, makes no difference. The rubber grease you have used is the correct one for rubber, although I would strongly suspect the rubbers are resistant to oil as well, taking into consideration where they live.
The small gap visible, I would not worry about at all.
Why you want to loosen and tighten the bolts is not clear to me at all.
