This proposal won't work. You call the proposed operation a "gift", but really it is a transfer. The whole point of even having SP in the first place is that it's not conveniently transferrable or fractionable, and therefore hard to sell [1].

If you make Steem Power transferrable, then you're setting up the conditions for there to be an open market for Steem Power, which will basically make Steem useless (why transfer Steem when you can just transfer an equivalent amount of Steem Power) and make it so Steem Power is no longer a long-term commitment (because you can just "gift" your Steem Power to someone paying you bitcoins).

If you want to spend your own STEEM to power up another account, the command line wallet already supports a transfer_to_vesting operation. I'm not sure if this feature exists in the web user interface, and I'm not sure if it should exist in the web interface because it might be confusing.

[1] It's technically possible to sell your entire account by changing your keys, or even to support dividing large SP balances by making some off-blockchain arrangement allowing parties to exchange ownership of fractions of some large account's SP. I've seen surprisingly little such activity to date, nor am I aware of any exchanges / brokers offering these kinds of activities -- all such activity I've seen was posts here or on Bitcointalk.