The thing I think people are missing is that Calder and 3JRF maintained a stalemate with Severanti for a year and a half singlehandedly, or very close to it. Laporte makes it quite clear that Home Fleet saw no action until Ganymede fell. We don't know if 2 Fleet sent any reinforcements rimward, but they're pretty much intact even at the end of Tenabra, so it seems reasonable that they were few, if any. Severanti was trying to fight a war of attrition, but the Feds had an overwhelming logistical advantage that he was unwilling to attack.
Here's a data point: Capella had a few million inhabitants, and was considered a large colony. This puts the population of the GTVA (well, the Terran wing, at least) at easily under a billion. Modern Earth has something like two orders of magnitude more inhabitants than all the Terrans in the GTVA, and the UEF has colonies of their own. Their economy is better than the Tevs', per capita, as well. They don't need to make intrasystem jumps to deliver war materiel, their logistics are untraceable due to their ability to dry-fire intrasystem gates... the Kadmos techroom entry even says they could establish a prosperous trade route across the entirety of GTVA space if they wanted to. The Feds may have only one system, but in every other measure of a civilisation, they're huge, relatively speaking.
What the Feds don't have is the ability to turn that economic advantage into war materiel. To remain competitive, they'd need to retool shipyards, expand procurement of militarily relevant raw materials, and otherwise refactor their economy. We actually saw a little bit of this with the Sanctus and Narayana refits; the Sanctus in particular was originally a freighter with enough firepower to function as a screening element. (I can't recall if these upgrades were in response to Tev aggression or the Gef campaign, but either way, the precedent is there.) Given a little bit of downtime, they could do it, and that's exactly what Severanti would give them.
The question is whether they would take it. I say yes. Byrne may be Ubuntu/10, but he commands Narayana artillery all the same. The Elders created the Fedayeen. Even if they refused to commit assets directly, surely Ubuntu would require they support their Jovian comrades with repairs, block upgrades, and medical care. Severanti's strategy would end with the GTVA grinding itself away at the node, while Sol's overwhelming economy gives them even stronger defenses as the war goes on, while the Tevs' already tenuous popular support wavers with each squadron or warship they bleed away. In short, Byrne would have his way, and the GTVA would exhaust itself on the Feds economic judo.
Comparing evacuating a space station to civil defense doesn't work. Responding to a tornado doesn't get harder just because you have more neighbors. I don't know if I buy that it's economically feasible to maintain enough space suits (keep in mind that they'd all need to be kept in working order separately) and procedures to get everyone to one, but it doesn't help. A suit just doesn't have the thrusters or fuel to clear an exploding Kumari, let alone dodge BBlues and Eos torpedoes (or even fighters - recall Kassim's comment about hitting an ejected pilot in Post Meridian). Furthermore, not only would your civilians not have a nice thick hull to hide behind, they'd have to be picked up independently, which would take far, far longer than picking them up from a docking bay.
Space suits wouldn't have helped at either Artemis or Simak.