This only applies for regular treatment of dandruff/seborrhoeic dermatitis, my own dermatologist even told me I need to use Nizoral indefinitely once a week for prophylaxis against seborrheic dermatitis.
You're right though, only use Nizoral if you can tolerate it. I recognise that 2% Nizoral can be harsh but since clinical studies prove it's the most effective formulation against Androgenetic Alopecia then my recommendation would be this:
-Try using 2% Nizoral and then follow with a moisturising conditioner (leave said conditioner on the scalp for 2-3 minutes)
-If that proves too harsh, try stepping down to 1% Nizoral using the same conditioner afterwards,
-If the latter still causes dry hair/scalp or irritation due to sulphate sensitivity, then by all means use an alternative ketoconazole shampoo.
In my own experience, back in March 2015 when I used 2% Nizoral alone to to treat a relapse of seborrhoeic dermatitis, I did notice that my hair looked dry and limp.
Fast forward to 16 August 2015 when I implemented it as part of my Androgenetic Alopecia treatment regimen, twice weekly. I started using Tresemmé Naturals Nourishing Moisture Conditioner immediately after each Nizoral use, leaving it in for 2-3 minutes and I had no such problem with dry hair like I did in the past. This conditioner contains aloe vera and avocado oil and is moisturising to the fullest extent. This is just my experience though, your mileage may vary.