Yes, it is intentional.
When we were defining the improvements to the election system that were rolled out in the spring we realized that including the questionnaire in the election page as opposed to on the child meta site meant that we needed to think about the possibility that someone might realize the election was going on shortly before the nomination period ended and would only have time to nominate themselves and write their nomination statement. Or, even beyond that potentially unusual chain of events, the questionnaire has simply always been editable on meta and we'd likely have people frustrated if it wasn't!
This meant that we needed to give space to allow the questionnaire to be edited - or even created - after the nomination period had ended. When discussing it internally, it was determined that it would be somewhat complicated and likely confusing to only allow the questionnaire to be edited but not the nomination statement itself.
In the end, we made the decision to go with the solution you see - while no new nomination can be created after the deadline, they can be edited.
In all honesty, I don't remember discussing whether comments would be locked or not as part of it. I remember talking about how one of the main concerns I had with moving the questionnaire to the election page was that there wouldn't be a comment section just for the questionnaire itself and we discussed the amount of content on the page during the voting phase.
I think there's likely more work to be done in the future to improve issues around comments on nominations - many concerns have come up recently over the facts that they're only available during the nomination period and aren't visible on the primary/election pages at all. It's a balance between making the election page easy to use and not an endless scroll of content and making potentially important information visible.
Our focus was about getting the questionnaire more visible - by putting it on the election page rather than hidden away on meta behind a link. The comments became an issue because comments on nominations were always locked when voting started but the addition of the questionnaire created a frustration for people who were used to the questionnaire being a meta post that could be commented on at all times. While there may have been grumbles about comments being absent on the voting page, it wasn't seen as a major concern.
The issue is, including the nomination, questionnaire, and comments - and leaving comments open for the entire election - feels like a lot of content on one page unless we collapse comments entirely - which means that, for the most part, most people still won't really be aware that they exist other than the "Show n more comments" button.
We probably don't have that balance perfect yet but I'm going to need to really understand why we locked comments and didn't bring them to the voting page in the first place before any decisions are made.