Karelia can have, if everything is put in there after his idea of a Ukr attack (7 inf 2 arm), the extra armor, 2 fighters, the 4 infantry from Russia and 8 more built, plus the extra infantry. Total 13 infantry, 1 armor, 2 fighters. Not as many as he claimed, but more than you did. The question is whether putting EVERYTHING there is a good idea.
Also, if I remember correctly, EE starts with 3 infantry and Finland-Norway starts with 2 or 3 (I think it was 3). You can actually put 6 infantry (or 5 if I’m wrong) into the attack on Karelia in other words if Ukraine is attacked (this is also true if Finland-Norway is attacked instead, but you can use more armor then since both of the Ukr ones survived), not 3, and 2 more if your baltic transport survived the Russian turn. I’m not saying this is a good idea, but it is a possibility. I still doubt you can claim Karelia though without luck playing a factor. But that’s what A&A is about sometimes… taking a risk with uncertain odds for a big prize - or complete and utter ruin. Maybe the attacking retreat option is a Godsend after all?