What is Paul really talking about here?
The latter part of the chapter helps. Try the high lighted portions.
14 I know, and am persuaded by the Lord Jesus, that there is nothing unclean of itself: but to him that esteemeth any thing to be unclean, to him it is unclean.
15 But if thy brother be grieved with thy meat, now walkest thou not charitably. Destroy not him with thy meat, for whom Christ died.
16 Let not then your good be evil spoken of:
17 For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.
18 For he that in these things serveth Christ is acceptable to God, and approved of men.
19 Let us therefore follow after the things which make for peace, and things wherewith one may edify another.
20 For meat destroy not the work of God. All things indeed are pure; but it is evil for that man who eateth with offence.
21 It is good neither to eat flesh, nor to drink wine, nor any thing whereby thy brother stumbleth, or is offended, or is made weak.
22 Hast thou faith? have it to thyself before God. Happy is he that condemneth not himself in that thing which he alloweth.
23 And he that doubteth is damned if he eat, because he eateth not of faith: for whatsoever is not of faith is sin.
Why don't you want to you want to talk about these verses found in the same chapter -
5 One man esteemeth one day above another: another esteemeth every day alike. Let every man be fully persuaded in his own mind.
6 He that regardeth the day, regardeth it unto the Lord; and he that regardeth not the day, to the Lord he doth not regard it. He that eateth, eateth to the Lord, for he giveth God thanks; and he that eateth not, to the Lord he eateth not, and giveth God thanks.
7 For none of us liveth to himself, and no man dieth to himself.
8 For whether we live, we live unto the Lord; and whether we die, we die unto the Lord: whether we live therefore, or die, we are the Lord's.
9 For to this end Christ both died, and rose, and revived, that he might be Lord both of the dead and living.
10 But why dost thou judge thy brother? or why dost thou set at nought thy brother? for we shall all stand before the judgment seat of Christ.
11 For it is written, As I live, saith the Lord, every knee shall bow to me, and every tongue shall confess to God.
12 So then every one of us shall give account of himself to God.
13 Let us not therefore judge one another any more: but judge this rather, that no man put a stumblingblock or an occasion to fall in his brother's way.
You've effectively changed the subject of the post you responded to. Verse 5 and 6a clearly speak about a day.
Paul is speaking about judging another and causing a dividing destroying feud. And for what the vanity I'm right so comply or go to hell. Paul also speaks about the liberty we have in Christ and some came in the church to cause trouble and bondage. They required Judaism be practiced to be a Christian. The Jews hated Christians. It is well documented in Acts and the issue carried on in the churches as evidenced by several epistles/books.
The pro grace people allow you to worship on the Sabbath without objection. This would be in line with the above text from Romans. The pro law people demand one worships on the Sabbath or forfeit their salvation. This is judging another's servant which you have no authority to do. You have no leg to stand on. There is no salvation in Judaism or the covenant that regulates them issued at Sinai.