Shannow is right on this one, Fionwe, as amusing as this argument is. I suspect that you've stuck to your guns for the fun of it, but let's clear a few things up before this continues further than it needs to. Even without the fact that One Power can create impenetrable barriers to matter, it's easy to circumvent your objections.

You claim that there is no viable method for Ishamael to creating a gateway with one end on Earth and one in outer space (or, similarly, one into the Mariana Trench), without the creator of this gateway committing suicide. Consider this simple method:

1. Ishamael opens a gateway facing away from himself.

2. The other end of the gateway is one mile below him, under the water (this is plenty deep for our purposes).

3. Ishamael ties off the weave and makes a separate gateway to somewhere else far away (the escape).

Ideally, #3 would be performed first for quick evacuation. In fact, the best would be to create #1 and #2 through gateway #3. Similarly, using this tactic, one could create gateway-jumps and make gateway openings arbitrarily far away from one's starting location.