Avoiding direct conflict is if TW aquiece to blockade. Direct conflict is if TW/US tries to run/break the blockade and triggers direct shooting conflict.
That said, blockade is legally act of war already, but in context of (also legally) ongoing PRC-TW Chinese civil war the point is moot. There's already conflict, but PRC will likely start with "quarantining" break away province through police actions by asserting control over inbound and outbound traffic (air and sea), most likely via coast guard doing the enforcement with Navy as backup. TW could either accept public loss of defacto sovereignty and PRC would likely ensure continuity in most traffic to island, i.e. life goes on mostly normal and maybe such arrangement becomes a workable status quo short of war. Alternatively PRC can salami slice quarantine into proper embargo/blockade - prevent transit of goods like weapons, food, energy, imports/exports, passenger flight to pressure TW into political reunifcation process over time. Then it's a matter of when/if TW/US challenges, after which the conflict will escalate to whoevers willing to bear more costs.
That said, blockade is legally act of war already, but in context of (also legally) ongoing PRC-TW Chinese civil war the point is moot. There's already conflict, but PRC will likely start with "quarantining" break away province through police actions by asserting control over inbound and outbound traffic (air and sea), most likely via coast guard doing the enforcement with Navy as backup. TW could either accept public loss of defacto sovereignty and PRC would likely ensure continuity in most traffic to island, i.e. life goes on mostly normal and maybe such arrangement becomes a workable status quo short of war. Alternatively PRC can salami slice quarantine into proper embargo/blockade - prevent transit of goods like weapons, food, energy, imports/exports, passenger flight to pressure TW into political reunifcation process over time. Then it's a matter of when/if TW/US challenges, after which the conflict will escalate to whoevers willing to bear more costs.