Aseh V'lo Saaseh

In this post, Chaim B. tackles the question of the Maharatz Chiyus (posed here) by discussing a situation where we have one mitzvah that is both a lav and an aseh. He writes as follows:

Kiddushin 34 gives examples of mitzvos aseh which are not zman gerama which women therefore are obligated to perform: hashavas aveidah, ma’akah, shiluach hakan. Tosfos asks why it is relevant whether these mitzvos are zman gerama or not - since each of these mitzvos also is linked to a lav which women are obligated in, women have to perform the action associated with the mitzvah irrespective of the aseh.Tosfos answers by devising cases where the aseh applies without the lav. The Ramban, however, offers a more fundemental argument. In these cases the lav does not function as an independent issur, but is the Torah’s way of strengthening the mitzvas aseh – if the aseh does not apply, the lav which goes hand in hand with it does not apply either.The debate between Tosfos and Ramban seems to be how to understand intersecting lavim/mitzvos – do we treat each factor independently, or do the aseh and lav merge together and function as one unit either based on the criteria of the aseh (in these cases) or the lav (perhaps in other cases).

A commenter, Anon1 makes the following comment on this Ramban:

I remember when R'Mayer Twersky explained this machlokes rishonim -- he gave two mehalchim -- one focusing on whether the aseh and the lav were concurrent or not and the other focusing on the mechanics of aseh docheh lo taaseh (hutrah vs. dechuyah).

First, I'm not sure what Anon1 means by explaining this Ramban as having to do with aseh docheh lo saaseh. There is a separate issue also mentioned by Chaim B. in this post as follows:

why can’t women, who are not obligated in the aseh of Yom Tov because it is zman gerama, use this oil for hadlakas neiros – since they are only obligated in the lav of Yom Tov, we should invoke aseh doche lo ta’aseh?
Tofos answers that since the lav of Yom Tov is conjoined to an aseh, it indicates (is a siman) that this lav is stronger than other lavim and cannot be pushed off by an aseh.

This issue is obviously relevant to aseh docheh lo saseh. The issue is if you have a mitzvah that is both an aseh shehazman grama and a lav, do we say the rule of ein aseh docheh lo saaseh v'aseh for women. Clearly, that issue may be related to how the rules of aseh docheh lo saaseh work.

The first issue is a different one altogether. That issue is whether women are chayav at all in a mitzvas aseh shehazman gerama that also has a lav associated with it. Meaning, even though they are clearly patur from the aseh part, are they still chayav in the lav aspect.

I looked at the Ramban and my understanding was that the Ramban was saying that it depends on how we phrase the lav. In a case like maakeh for example, how do we understand the lav? Is the lav:

Do not refrain from putting up a maakeh.

Or is it:

Do not refrain from performing the mitzvah of maakeh.

The Ramban says that it all depends on how the lav is written in the Torah. In the cases above (maakeh, hashavas aveidah, etc.) we read the lav in the latter sense. The lav is to not refrain from the mitzvah. Therefore, if the aseh is zman gerama and, thus, there is no mitzvah, there is no lav either by extension.
In my understanding of the Ramban I did not think the Ramban was making a general rule by all mitzvos that have an aseh and a lav. Rather, the Ramban would analyze each case differently to determine how exactly the lav is phrased.