Why are the Turks using M60 Sabra Tanks instead of their Leopards in Syria?

I asked on an earlier blog post why the Turks were using their M60 Sabra MBTs in Syria instead of their Leopards.  According to Wikipedia the Turks have around 300 Leopards but we haven't seen them in action except during the coup attempt.  SvD, a reader of this blog,  has this explanation...

The M-60 Sabra is the only tank in Turkey's arsenal that has modern armor, to withstand ATGM hits.
The Leopard 2A4 is the vintage version...

That couldn't possibly be true could it?  A 1960's era tank with add on armor is more survivable than a more modern design?