I'm a bit confused. You "believe it is an amended Form 1040x" that you are preparing, are looking at?

"Am I correct in saying taxpayer paid full FICA Tax on the Original Form 1040, Schedule C Net Profits?"

We cannot see their form(s). You would confirm the data and do some math. Your issues for Sched 1 and 2 are the same issue; you would confirm if that data is correct for the additional tax owed and for the deduction for the 50% owed.

And, as @Just-Lisa-Now- points out, the Sched SE should show Medicare computed, which has no limit, and SS only to the limit, for the combination of W2 + Sched C for the same person when that person exceeds the max for SS.