The proof texts you quote from WCF 2.1 are given to support the words in bold: " There is but one only, living, and true God, who is infinite in being and perfection, a most pure spirit, invisible,
without body, parts, or passions; immutable, immense, eternal, incomprehensible, almighty, most wise, most holy, most free, most absolute...."
Considering the fact that the proof texts refer to physical images and body parts, I believe someone (like Ulster Fry Phil) can claim to be confessional on the grounds that WCF 2.1 can be interpreted as not saying anything about DDS and is simply stating that God has no physical body or physical parts, as you seem to suggest can be a valid definition of "simple":
He (Ulster Fry Phil) has pretty much said this in #103 and #151:
If part of the issue is understanding what the Divines intended in the Confession, one must consider how they used the term "parts" elsewhere. For example, "By this sin they fell from their original righteousness and communion, with God, and so became dead in sin, and wholly defiled in all the parts and faculties of soul and body. (WCF 6.2)
Consider that a fairly standard and well-regarded treatment of the Confession (
Robert Shaw's Exposition of the Westminster Confession of Faith, 1845) sees the "without body, parts" in WCF 2.1 in the context of affirming "opposition to the Polytheism of heathen nations, and to the heresy of the Tritheists, who hold that there are three distinct Godheads, or that one Godhead is divided into three distinct parts." (II.1) and that "God is a most pure Spirit,– that is, he is an incorporeal, immaterial, invisible, and immortal Being, without bodily parts..." (II.3). You do not come away from Shaw thinking WCF 2.1 was written to enshrine DDS but rather that it was simply (groan) teaching that God (1) does not have a body or body parts and (2) that the Trinity is 3 persons not three parts of 1 person.
Adding a specific (narrow, metaphysical) interpretation to WCF 2.1 and what is meant by "parts" in order to accuse someone of not being confessional is not something I can support. In other words, you can believe WCF 2.1 is referring to DDS or not, and you can even debate it (for the good of all, mind you), and your particular church may require a specific interpretation for ordination, but that should not become a shibboleth for fellowship, online or otherwise.