It's about Iran's intention. Iran is the victim here. Iran's behaviour is a response to non-compliance by other parties. In fact, Iran by not immediately withdrawing has demonstrated the following: "Upon receipt of the notification from the complaining participant, as described above, including a description of the good-faith efforts the participant made to exhaust the dispute resolution process specified in this JCPOA,..." - Article 37
Wait, in the Article 36 & 37:
36. If Iran believed that any or all of the E3/EU+3 were not meeting their commitments under this JCPOA, Iran could refer the issue to the Joint Commission for resolution; similarly, if any of the E3/EU+3 believed that Iran was not meeting its commitments under this JCPOA, any of the E3/EU+3 could do the same. The Joint Commission would have 15 days to resolve the issue, unless the time period was extended by consensus. After Joint Commission consideration, any participant could refer the issue to Ministers of Foreign Affairs, if it believed the compliance issue had not been resolved. Ministers would have 15 days to resolve the issue, unless the time period was extended by consensus. After Joint Commission consideration – in parallel with (or in lieu of) review at the Ministerial level - either the complaining participant or the participant whose performance is in question could request that the issue be considered by an Advisory Board, which would consist of three members (one each appointed by the participants in the dispute and a third independent member). The Advisory Board should provide a non-binding opinion on the compliance issue within 15 days. If, after this 30-day process the issue is not resolved, the Joint Commission would consider the opinion of the Advisory Board for no more than 5 days in order to resolve the issue. If the issue still has not been resolved to the satisfaction of the complaining participant, and if the complaining participant deems the issue to constitute significant nonperformance, then that participant could treat the unresolved issue as grounds to cease performing its commitments under this JCPOA in whole or in part and/or notify the UN Security Council that it believes the issue constitutes significant non-performance.
37. Upon receipt of the notification from the complaining participant, as described above, including a description of the good-faith efforts the participant made to exhaust the dispute resolution process specified in this JCPOA, the UN Security Council, in accordance with its procedures, shall vote on a resolution to continue the sanctions lifting. If the resolution described above has not been adopted within 30 days of the notification, then the provisions of the old UN Security Council resolutions would be re-imposed, unless the UN Security Council decides otherwise. In such event, these provisions would not apply with retroactive effect to contracts signed between any party and Iran or Iranian individuals and entities prior to the date of application, provided that the activities contemplated under and execution of such contracts are consistent with this JCPOA and the previous and current UN Security Council resolutions. The UN Security Council, expressing its intention to prevent the reapplication of the provisions if the issue giving rise to the notification is resolved within this period, intends to take into account the views of the States involved in the issue and any opinion on the issue of the Advisory Board. Iran has stated that if sanctions are reinstated in whole or in part, Iran will treat that as grounds to cease performing its commitments under this JCPOA in whole or in part.
We see that there are built in protocols to formally submit complaint. In the end of Article 37, Iran has specifically opened the option: "Iran has stated that if sanctions are reinstated in whole or in part, Iran will treat that as grounds to cease performing its commitments under this JCPOA in whole or in part."
Am I missing something here?