Why does Antinous want to kill Telemachus?

Telemachus is a barrier between the suitors and Penelope. Telemachus insults the suitors in the first two books of the Odyssey, and threatens to eventually kill them. If Telemachus is dead, then there will be no man in the house. Penelope will be forced to marry. Further, it is easier to kill him before he is full grown.