This article details multiple viewpoints on the issue. I am excerpting the end / author's conclusion. Readers can agree or disagree, or better, follow M.Y.'s adage of consulting their Rav:
Common practice among our community is to host non-observant relatives
for Yom Tov. Moreover, it is common practice for observant Jewish
hotel owners to host and feed Jews who are obviously non-observant.
Outreach professionals routinely invite non-observant Jews for Yom
Tov, especially for the Seder. People either rely on the opinions that
this prohibition does not apply to non-observant Jews or that
contemporary non-observant Jews are regarded as Tinokot SheNishbeh’u.
It is certainly preferable in such a situation to cook all the Yom Tov
food in advance in order to eliminate concern for violating a Torah
level prohibition. In any event, the Halacha (Mishnah Berurah 495:5)
prefers preparing food before Yom Tov so as not to be preoccupied with
food preparation during the holiday.
Rav Shlomo Zalman Auerbach (ad. loc.) laments the inability to
properly observe this Halacha in today’s circumstances. Nonetheless,
we should aspire to create highly joyful and spiritual Yom Tov
atmospheres in our homes that will inspire non-observant Yom Tov
guests to return to a life of Torah observance.
It is ironic that we rely on the opinions that contemporary
non-observant Jews are compared to a Tinok SheNishbah in regard to
inviting them for Yom Tov. However, in many circumstances we rely on
Rav Moshe Feinstein’s opinion that today’s non-observant Jews are not
classified as Tinok SheNishbah, and are considered to be invalid
witnesses. These circumstances include situations regarding a child of
a woman’s second marriage who did not receive a proper Get from her
first husband. In such cases, we embrace Rav Moshe’s opinion that the
child is not a Mamzeir (illegitimate) if all witnesses to the mother’s
first marriage were non-observant. (For further discussion of this
issue, see Gray Matter: Volume One pages 83-92.) While there are ways
to resolve this inconsistency, it highlights the fact that Rav Moshe’s
ruling should be relied upon only if no other options exist. We should
all make efforts to ensure that civilly divorced non-observant Jews
should receive a proper Get even if they were married in a
non-Orthodox ceremony where all witnesses were non-observant Jews. Our
discussion raises the very distinct possibility that non-observant
Jews are not necessarily disqualified from serving as witnesses, since
they may be regarded as Tinokot SheNishbe’u.