Sure, there are definitely second and third order effects. Taxing shareholders may reduce the incomes of wealthy people, who have a higher savings rate, leading to a reduced national savings rate, higher interest rates and lower asset prices, which could cause some businesses to decide against doing certain investments that wouldn't have a high enough return (relative to the interest rate on that capital).

Since everything is tied together it's hard to reason through all of this. For companies making investment decisions the interest rate will obviously be one factor, but projected consumer demand will be another, and it's easy to imagine in some cases higher middle-class incomes and consumer demand might be more important than a lower interest rate for decisions around building new factories etc.

Obviously it's complex and I don't have a strongly-held opinion. But taking a historical perspective interest rates are near record lows and financial asset prices are at record highs. On those grounds policies that might nudge us back a little into where the economy has been operating for the past 50 years (regarding interest rates etc) seem less risky than ones that push us further away from our post-WWII historical experience.