Nothing in Scripture says Matthias is not an apostle, for your reason or any other. That is an assumption imported into the text by the reader who is bringing his presuppositions into the text about the way God's guidance is supposed to work.
Ransom we are debating remember? As far as I'm concerned this is not a contest of wills or who is right or who is wrong or more spiritual, etc.
Rather than continue in this atmosphere of animosity, I'll give you my opinion, yes it's an opinion because to me the Scripture is not 100 percent clear.
First of all the word "apostle" appears in the Scripture in other places in the original language:
2 Corinthians 8:23 Whether any do enquire of
Titus, he is my partner and fellowhelper concerning you: or our brethren be enquired of, they are the
messengers of the churches, and the glory of Christ.
Philippians 2:25 Yet I supposed it necessary to send to you
Epaphroditus, my brother, and companion in labour, and fellowsoldier, but your
messenger, and he that ministered to my wants.
The word "messenger" is "apostolos" in both these passages, so now we would have 17 apostles (among others) who were "sent" if we simply looked at the word itself.
Strong's: 652 apostolos {ap-os'-tol-os}
Meaning: 1) a delegate, messenger, one sent forth with orders 1a) specifically applied to the twelve apostles of Christ 1b) in a broader sense applied to other eminent Christian teachers 1b1) of Barnabas 1b2) of Timothy and Silvanus.
The KJV translators did a pick and choose where and when to translate the word as "apostle", "messenger" or one who was "sent".
There can only be 12 (Capital A) Apostles (IMO) specifically because of the action and requirements of the Apostles in Acts Chapter 1:
21 Wherefore of these men
which have companied with us all the time that the Lord Jesus went in and out among us
22 Beginning from the baptism of John,, unto that same day that he was taken up from us, must one be ordained to be a witness
with us of his resurrection.
So, that person who was to take Judas place had to have been one who had accompanied Jesus and the apostles from the baptism of John and been a witness of the resurrection with then
"with us".
Pesonally I cannot accept the view that the Revelation passage is a metaphor of the "12 apostles", so if one accepts the conditions laid down by the 11 Apostles then Paul cannot be one of the "12 Apostles".
"who is the 12th apostle"?
I don't know, would be my answer to my own question
It would seem to me to have to be Matthias or Paul, but I don't know, I guess I'll have to wait and see.
There is another possibility I suppose. There is the same difficulty when one tries to list the 12 tribes of Israel and take into account Joseph's two sons Ephraim and Manasseh who are also numbered among the twelve tribes in the various OT lists, although in the Revelation Joseph is included, Manasseh is included but Dan is missing even though every list in the OT includes Dan (I believe).
Maybe there will be a shared Capital A Apostleship: Matthias-Paul as there is a shared tribal authority of Israel : Joseph-Manasseh-Ephraim.
So, I guess I'll just have to wait and see.
If I were forced to choose, I would say Matthias but what to do with Paul?
Please note that I never said Matthias was NOT an apostle but treated their choice as a "what if" (in terms of being a wrong choice) for the sake of the debate.
HankD