A 40-50% reduction in share price would have most probably eliminated the dividends completely, especially in a very adverse deflationary market, which most definitely would have seen the most of that $10 billion sum allocated to other things than R&D.
Pfizer's cash situation or ability to spend/pay a dividend has nothing to do with stock price. Pfizer does not have their cash balance invested in other stocks. Ability/willingness to pay a dividend has to do with excess cash.
To the extent there's any relation, it's a high stock price that discourages paying a dividend. If the dividend yield will be basically nothing, why bother spending down precious cash that could be reinvested (because obviously the market values future cash flows a lot more than current ones).
Deflation might encourage a little bit of holding of corporate cash rather than spending it on R&D, sure. But even then I think you're overstating the case.
