I would encourage you to email, call or WhatsApp Richard or Marion. They have the reputation of being good people. I do not think that it is a scam in the sense that they operate a very legitimate operation and are totally capable and, I am sure, fully intend to deliver on their commitment to you.
This being said, 2020 and early 2021 have been extraordinarily difficult for safari operators with essentially very little to no revenues and still substantial expenses (land leases, vehicle loans, lodge mortgage, payroll, etc.)
All operators are suffering. It is murmured that possibly up to 30% of safari operators will not economically survive COVID. I do not know where the number comes from, but there is no doubt that some operators regularly operate on very tight cashflow, do not have substantial borrowing capability, and do not have the reserves to survive one or two years without income. This is less an issue for larger operators who are well funded, own substantial collaterals, and have the wherewithal to wait and survive at least one year and possibly two years, but this is dramatic for small operators.
I have no idea what financial stress Richard Holmes Safaris can or cannot withstand, and I am reasonably certain that they do not make this cash call without reason, but this is not necessarily a predictor of failure. Therefore, in view of the above I would say in general that the risk in such cases is not a "scam" in the usual sense, but the very real possibility than some operators have gone, and will go bankrupt during the COVID crisis and will not be able to honor hunts they booked and for which they received deposits in good faith.
The Huntershill group (Huntershill Safaris, Comre Safaris, Huntershaven, Rocklands, Cherokee, Vetvlei Safaris) has actually been able to use the mostly dead 2020 season and the weak beginning of 2021 to invest into the operation and upscale the comfort of our various lodges, doing all sorts of facilities work easier accomplished when clients are not here, but I also know of some other operators who are really hurting for cash...
Each will make their own decision, but an act of kindness in helping them bridge-fund may go a very long way in building a friendship for life with your safari operator...
I hope this gives context to your situation and your question...
Thx
P