I think this discussion is heading in the wrong direction. Magus' battle techs are only Magus' abilities that are practical for fighting, they don't encompass all that he's able to do, so personally I see no reason to pick them apart to the point of ringing eachother's collective necks over it.
Here are some of the facts:
Magus, if not all shadow magic users, does at the very least control space.
+Instead of running when the party runs, Magus floats, most likely controlling gravity, or possibly magnatism, to do so.
+Magus summons Lavos. A summon is either the teleportation of a being from one location to the caster's current location on the same plain of exsistence, or the transfer of a being from one plain of exsistence to the caster's current plain of exsistence. Any teleportation is a manipulation of space, displacing something form point A to point B.
+Instead of running or even floating up to enemies that Magus wants to slash with his scythe, Magus does a short teleportation there. As stated above, any type of teleportation is a manipulation of space.
So yes, Magus can manipulate space to a certain degree. Time on the other hand is a trickier thing to figure out, since Magus has never directly used any such technique. We do know a few things, though.
+Magus' Lavos summoning gone wrong does propel everyone to different time eras, however...
-This is probably due to Lavos' involvment, since we know chaotic, time-related things seem to happen whenever
Lavos is around.
-Magus appears stuck in whatever time period the "Gateway Shuffle" throws him. Yes the quotation in the last sentence was a reference to Cowboy Bebop. It seems that Magus is stuck there, but there's always the possibility he always ends up going where he wants to be (at least while he's an adult).
-Magus, disguised as The Prophet, forces his sister to seal a time gate. He does not seal it himself. This may be because he cannot, or it may be because Magus didn't want to blow his cover as The Prophet.
+Magus' genealogy and the magical abilities of his family members is a strong indication, however, that Magus may be able to manipulate time. His sister holds a necklace, either made by her or her ancestors, that is capable of manipulating the time gates. Reasonably, Magus being of the same family means that he quite posibbly could have the same potential.
+At the end of the game (the standard ending) if you have Magus in your party, Lucca assumes that Magus is going to go look for his sister (or, that's the implication anyway). Lucca is extremely intelligent and would probably know whether Magus were capable of doing so or not.
So, like many things in CT, there is some flimsy evidence for both sides of the argument.
Edited for spelling and grammar.