I dunno...
Seems UP as is, with the Antlions coming up 4/4 for 2
, and having immunity to Explosions/Steals.
5/6 for 3
would probably be more balanced than 6/7 for 3
, because there you have 1 less cost than the Golem for the same attack, which is not always justified by the extra weaknesses.
On the other hand. 5/5 for 2
could be ok, if a tad OP. With a card like this, it's hard to balance.
(Making it 3/3 but changing the text to "Can only be targeted as a permanent" could well be UP or OP, it'd probably require testing)