Suppose all objects have an 'energy', whatever that is, given by a vector sum of two components: P and M. Now every object may be distinguished by the distribution among those components: if, for a given norm, the energy is all in P, we say it is spacelike, it's energy is all in the space component. If it's in M then it's timelike.
So for us massive timelike objects at rest, E=M (in natural units) and for spacelike objects, E=P. Then it becomes clear that, since the mass is an instrinsic property of objects, any given object with M>0 cannot be spacelike: the energy vector will always have a time component, and likewise light cannot be timelike. You can however increase the spacelike component of the object and make it approach spacelikeness, measured by, for instance, the angle teta=arctg(P/M) with diminishing returns for each unit of energy (if you visualize it, you'll se at the start the return is linear -- teta ~ P/M and then it becomes very hard).
So the explanation above is telling in the sense that if you could be spacelike things would be weird, but doesn't reveal why you can't have massive spacelike objects -- namely, because we have a finite supply of energy.
The problem with that explanation from a pedagogical point of view is that you have left the word "energy" deliberately undefined. Because it's undefined, your explanation is isomorphic to this one:
"Suppose all objects have a 'snorble' (whatever that is) give by a vector sum of two components..."
You also haven't defined M and P. I know you mean mass and momentum, but only because I already understand this stuff. If your target audience is someone who doesn't already understand it, you need to define your terms or your explanation won't be effective.
Suppose all objects have an 'energy', whatever that is, given by a vector sum of two components: P and M. Now every object may be distinguished by the distribution among those components: if, for a given norm, the energy is all in P, we say it is spacelike, it's energy is all in the space component. If it's in M then it's timelike.
So for us massive timelike objects at rest, E=M (in natural units) and for spacelike objects, E=P. Then it becomes clear that, since the mass is an instrinsic property of objects, any given object with M>0 cannot be spacelike: the energy vector will always have a time component, and likewise light cannot be timelike. You can however increase the spacelike component of the object and make it approach spacelikeness, measured by, for instance, the angle teta=arctg(P/M) with diminishing returns for each unit of energy (if you visualize it, you'll se at the start the return is linear -- teta ~ P/M and then it becomes very hard).
So the explanation above is telling in the sense that if you could be spacelike things would be weird, but doesn't reveal why you can't have massive spacelike objects -- namely, because we have a finite supply of energy.