No, the whole thing with Karelia was all about that standing obsession of Russian strategists, the security of St. Petersburg/Leningrad, which concern is as old as the city itself. The ’20 border was virtually in the suburbs of the city which obviously made the Soviets a bit uncomfortable. Do note the other relevant territorial concessions the Soviets walked away with: the scattered islands in eastern Gulf of Finland smack in the middle of the sea approaches to the Neva delta and the lease of the Hanko peninsula for fifty years, the base there serving to in combination with the Baltic possessions to the south to exercise control in depth over the Gulf sealanes. (This was replaced by a for all intents and purposes identical lease of the Hanko peninsula in ’45, which was close enough to Helsinki to also serve the purposes of intimidation should such be necessary.)

The Soviets obviously had far more reserves and were about to win by sheer attrition anyway (plus Timoshenko’s emergency reforms rather improved troop performance) but at that point the looming threat of Franco-British intervention drove them to the negotiation table. IIRC by that time the Finnish army didn’t expect to be able to hold on for more than a few weeks longer at best.

http://www.tankmuseum.org/

http://www.tankmuseum.org/ixbin/indexplus?_IXSS_=_IXMENU_%3d%26ALL%3dGoliath%26_IXACTION_%3dsummary%26%252asform%3d%252fsearch_form%252fbovtm_combined%26_IXSESSION_%3d8NNkuXniqdA%26TYPE%3darticle%26_IXFPFX_%3dtemplates%252fsummary%252f&_IXFIRST_=2&_IXSPFX_=templates/full/tvod/t&_IXMAXHITS_=1&submit-button=summary&_IXSESSION_=8NNkuXniqdA&_IXMENU_=Vehicles

http://www.tankmuseum.org/ixbin/indexplus?_IXSS_=_IXMENU_%3d%26ALL%3dGoliath%26_IXACTION_%3dsummary%26%252asform%3d%252fsearch_form%252fbovtm_combined%26_IXSESSION_%3d8NNkuXniqdA%26TYPE%3darticle%26_IXFPFX_%3dtemplates%252fsummary%252f&_IXFIRST_=1&_IXSPFX_=templates/full/tvod/t&_IXMAXHITS_=1&submit-button=summary&_IXSESSION_=8NNkuXniqdA&_IXMENU_=Vehicles