There may be US tax rules that are at play in the early exercise of options. Usually, in the absence of taxes or exceptional idiosyncratic conditions, it is best to leave the decision and cash flow of option exercise to the latest possible date. 

In the US, capital gains taxes apply to shares owned for more than 1 year, while shares held less than a year are treated as regular income. So, for $0.52 warrant holders of Poet, it may make sense to exercise the options now, so that as of March 2022, the shares can be sold and be taxed as capital gains (10% ?)rather than as regular income. (40% ?).

Tax savings at current share prices  already more than make up for the cost of carry for 1 year on the 52 cents spend. Of course, this is all predicated on someone like Don thinking that Poet's share price will be higher to much higher in a years time. If this is the case, I don't see someone like Don selling these shares this year.