It’s not ideal, but it’s not an impossible hinderance. The picture has a low power variable scope. At magnified levels, the front sight post becomes a thin shadow in the lower half. Noticeable but doesn’t impact much. At 1x magnification the front sight post does reach to where the reticle is, but the target area is still viewable.
With an LPVO the front sight post isn’t usable since the 1x setting isn’t “true 1x” but has a tiny amount of distortion, however with a red dot, the front sight post is still crisp, which means that if the dot dies it is easy to look through the optic and use the front sight.
When shooting with both eyes open for close range with an optic you get so much information from both eyes that the blockage by the post is essentially edited out by your brain.
The standard service issue M16 and M4s have/had fixed front sight posts and have been issued with optics for decades.