They cannot vote with common on a proposed share increase
And the dilution happens once the shares are issued, even prior to conversion.
Suppose somebody wants to buy for NWBO for $10B. Today that would be $6.67/ share. If, hypothetically they sell 2M Cs with attached warrants (100%) then the PPS of that $10B would then be about $6.27 (with a .7 strike on the warrants).
The point is that is true regardless of any raised in the auth share limit. And it is dilution.
P.S., as I said in a previous post, in 2017 LP required their votes in order to get in on the heavily discounted deal.