It's a question of total float that affects SP. If you increase total float, we can expect some changes in SP. Instead of 171 M shares, I should use the total float.
In terms of how much of the net assets, it's a complicated calculation to figure out what each share is now worth compared to earlier. The post by JBRR above shows how complicated the whole thing is.
There's two topics intermixed here: the effect of paying off the bonds in stock and the effect of short selling.
Short Selling
If you have a company worth $100 and they have issued 4 shares, those shares are worth $25 each. If a short seller decides to sell these 25% ownership shares to more than 4 people, then they've got >4 people running around thinking they own a quarter of the company, but it doesn't mean those those shares are worth less than $25. Regardless of any shortselling, a quarter ownership of $100 is always worth $25. You just have perhaps 5 people that own a quarter ($125) and 1 person that owns a negative quarter (-$25) for the same $100 net value.
So the simple act of short selling doesn't affect the share price directly. If someone promises me that I can own 10% of AAPL for $100, that would be a fantastic deal even if they have sold the same thing to a billion other people. I wouldn't decline to buy 10% of AAPL for $100 - I would gladly buy (assuming the seller had the US treasury like liquidity to recover from such a foolish move). Following through on that is their problem.
So let's say the shorts start dumping shares on the market. Those shares are still worth whatever percentage of the companies value they are equal to. If the price drops to less than that, they are a deal and a rational market would scoop them up.
So short selling in itself doesn't change the value of the shares. But there can be indirect effects. If the market is flooded and the price drops, that could be perceived by buyers a loss of interest in the stock, rather than the sale on shares that it is, so it creates the perception of negativity which can have an effect but not an easily quantified one. And the opposite is also true. When shorts cover they tighten up the supply of shares available will can increase the price, but again the value of the company hasn't changed so the shares just become overpriced temporarily. That's why short squeezes don't last (see VW). Short selling causes manipulative effects, but not long term fundamental effects.
Stock Issues
The value of a company is its net assets + future profits. Ignoring future profits for a minute, a company with $2 million in cash and $1 million in debt has a net value of $1 million. If they had two shares they'd be worth $500,000 each. If they decided to pay off that $1 million in debt by issuing two more stocks for $500,000, the company would then have the same $2 million in cash but no debt for a net value of $2 million. Since there are now 4 shares, the stock price would still be exactly the same. That is why your calculation of a $3 dip was wrong. You added to the share count but not the net assets. Total float is besides the point.
Of course stock issues can also affect expectations for future profit. In Tesla's case their future profits are highly dependant on their ability to grow, so the more they can free up cash by exchange debt for stock, the better. Sure the future profits are divided amongst more folks, but the future profits are also larger because there is an extra half billion dollars to invest in growth. So this sort of an action where debt is exchanged for stock is a good thing for Tesla as it improves their chances of realizing the hoped for growth. That's why TSLA has almost always risen after every share issue. We can safely say this share issue will be neutral or positive for the share price. The only reason why it wouldn't be is if the market thinks it also indicates some other negative news, like Tesla's doing this because they're not actually as profitable as thought. When secondary offerings in general cause a decline in the share price, it's not because of the secondary offering directly, but because it can indicate that the company is doing worse than hoped.
Bottom Line
Short selling and share issuances don't change the long term value of the shares due to simple dilution as you're attesting. There are side topics like hedging, but they don't change this fact.
