Using child soldiers for your philosophy experiment probably counts as something wrong.
That said, he would've had a much better chance by properly teaming up with Solid Snake (even if it was a temporary alliance) than he likely ever was with Ocelot - if he burnt the bridge with Ocelot after taking Big Shell and teamed up with Solid Snake, I think that Solidus would've had a much better chance at actually beating the Patriots, at the cost of crippling the US and basically creating a CoD plot (Soviet resurrectionists dealing a crippling surprise blow against the United States as a surprise tactic and waging war against the US using advanced technology). And to boot I would think that they would have to coup a large government's power base to wage such a war - if Gurlukovich Sr. was still alive, couping Russia would seem very plausible, but Ocelot kills that very early on. Olga was compromised by the Patriots and was non-viable for that task, and Dead Cell is mostly a group of schizophrenics who were at that point mostly dead. Solidus had far too few connected and powerful allies that he could trust in positions of leadership or as power brokers in his absence. Basically everyone betrays him in the end, either out of being compromised from the Patriots or because they were double-crossing him from the beginning.
In the long run, Ocelot's strategy of an army without a state (diet Outer Heaven) made a lot more sense for anti-Patriot action, and Solidus would only have a fraction of that power with the Gurlukovich mercs, even with their Arsenal Tengu getups (which would pretty quickly be surpassed by the FROG units and other cybernetic special forces as the Patriots rolled out the full war economy).