Cheryl Schatz

More proof that the “roll” was about ministry:

The author demands that no widow under 60 should be put on the official list of (widow) or allowed to serve as a deaconess in the narrower sense, since he fears that younger widows will marry again and will thus be untrue to their office and therewith to Christ.
-Theological dictionary of the New Testament. (G. Kittel, G. W. Bromiley & G. Friedrich, Ed.)

This list suggests that a widow should be qualified to offer service if and when called on by the church.
-Vol. 3: Evangelical commentary on the Bible. Baker reference library.

It is when these younger widows experience this kind of sensuality that they want to marry again, and this desire to remarry results in or is interpreted as a turning away from Christ, since, as verse 12 makes clear, widows who are included in the list are obligated to make a vow to serve Christ on a full-time basis and therefore should not remarry.
-Arichea, D. C., & Hatton, H. (1995). A handbook on Paul’s letters to Timothy and to Titus. UBS handbook series; Helps for translators (120).

Apparently there was a list of widows in the early church. This list registered widows who had dedicated themselves to ministry in such a way that they qualified for financial support by the church. As with any person dedicated to service (like pastors and deacons), certain characteristics must be evident in the candidate.
-Larson, K. (2000). Vol. 9: I & II Thessalonians, I & II Timothy, Titus, Philemon. Holman New Testament Commentary; Holman Reference (223).

cast off their first faith—namely, pledged to Christ and the service of the Church. There could be no hardship at the age of sixty or upwards in not marrying again (end of 1Ti 5:9), for the sake of serving better the cause of Christ as presbyteresses; though, to ordinary widows, no barrier existed against remarriage (1Co 7:39).
-Jamieson, R., Fausset, A. R., Fausset, A. R., Brown, D., & Brown, D. (1997). A commentary, critical and explanatory, on the Old and New Testaments.

The enrolment must have been for some kind of specific Christian work.
-Carson, D. A. (1994). New Bible commentary

But refuse to put younger widows on the list for when they feel sensual desires in disregard of Christ, they want to get married” We must remember the positive theology of marriage which is presented in the Bible (cf. Gen. 1 & 2). This phrase seems to relate to a vow that these widows took when they became house church helpers (cf. v. 12).
-Vol. Volume 9: Paul’s Fourth Missionary Journey: I Timothy, Titus, II Timothy. Study Guide Commentary Series (69). Marshall, Texas: Bible Lessons International.

No moral condemnation of remarriage is involved, nor is asceticism commended. The point is simply that a conflict may arise between ministry for Christ and the desire to remarry.
Kittel, G., Friedrich, G., & Bromiley, G. W. (1995). Theological Dictionary of the New Testament (420–421).