Based on the scenario you have painted, you also need to consider some other factors aside from what is being obvious to everybody who might want to pick borrowing over selling just by thinking tax is not going to be paid but some other things that are important are

1. What is the interest rate being charged and the duration of the loan. If the interest rate is more than the tax to be paid, then its not wise to go for it and again the duration, if its going to be too short to cause a distorted cashflow, then I wouldn't suggest going for the loan.
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2. What is your plan for your bitcoin is another important factor. If you so much love holding for a very long teem, then the loan is the best option because the appreciation that would accrue over it would cover for whatever interest you will have to pay but if your reason for using it as collateral is because price is low now and you would sell the moment price increases and there is no certainty that it will happen anytime soon and you might ended up losing on two ends. One the interest and secondly the low price might have to eventually sell.